There is certainly no lack of tools -- ones that are good and free -- to help you create PDF documents. But what if you have a job where you need to make new PDFs and your sources are already-created PDF documents? Or if you need to update your company's finished PDFs? The choice of applications that actually allow you to change a PDF after it was created is more limited.The best-known tool is, of course, Adobe Acrobat, and no wonder: Adobe Systems created the PDF standard. However, Acrobat is not inexpensive; prices begin at $299 for the Standard version.For this roundup, I compared Adobe Acrobat X Standard (the latest version of the application, which will be released within the next few weeks) to these three competing applications: Foxit PDF Editor 2.2, Nitro PDF Professional 6 and Nuance PDF Converter Professional 7. All of the competitors cost $99.99, considerably less than Acrobat. I tested them on two Dell laptops: one equipped with a 1.86-GHz Pentium M processor, 4GB of RAM and Windows 7 Home Premium (64-bit); the other with a 2.2-GHz Pentium Dual-Core processor, 2GB of RAM and Windows Vista Business (32-bit).For the sake of the test, I used a PDF version of an IRS document (specifically, the W-9 form), so that I could work with something that used fill-in fields as well as explanatory text. (I hasten to add that any changes made to the documents were immediately discarded.)All of these applications let you load a PDF document into them so you can make changes to its content. I looked them over with an emphasis on ease of use when it comes to editing the text and manipulating the graphics, relative to the value of their price.Adobe Acrobat X StandardAs this roundup was being researched, Adobe announced the imminent release in mid-November of the next version of Acrobat. The company gave me access to a review copy of Acrobat X (in other words, Version 10).Acrobat X Standard ($299) is the basic version of Acrobat. It's the lowest-price option among the three versions of Acrobat that allow you to change around words and graphics in PDF documents (the free Adobe Acrobat Reader only lets you view PDFs, not edit them).The new version offers several features not available in Acrobat 9 Standard, including a Reading Mode that hides everything except the document itself and the menu bar, the ability to more easily convert Microsoft Office documents to PDFs, and a streamlined interface. It also removes "hidden" information in the document that could create privacy or security problems.Adobe also sells two other versions: Acrobat X Pro ($449), which adds features for high-end print production; and Acrobat X Suite $1,199) which adds multimedia features such as Photoshop image editing and video encoding.User interface: Documents loaded into Acrobat take up a main viewing area. A sidebar along the left side of your document has icons that let you open side or bottom panels to display thumbnails of the document's pages, its bookmarks, digital signatures that have been signed to it, comments provided by people and any files attached to it.Working with PDFs: Using the Edit Document Text tool, you position the cursor at the point in the document where you want to insert new text, and type. The backspace and delete keys work like they normally do in a typical text editor, and you can use the mouse to highlight words, letters and other characters.You can manipulate the size of a body of text. When you select the Edit Object tool and click on a row of text, the application surrounds it with a rectangle, marked with four anchor points at the corners. Clicking, holding and dragging any of these corners inward will shrink the text font size, and dragging outward will increase it.Click anywhere within the rectangular boundary, hold the left mouse button, and you can drag the row of text to place it in another part of the document.(One thing to keep in mind when you edit text in a PDF document: The lines of text don't automatically "wrap." If you add more words, the row will extend toward the right. If you remove text, the row's length will shorten. But in either case, the row below it will not automatically link to the end of the row you edited, and the flow of the rest of the text in the paragraph will not automatically be reformatted.)What works well: With Acrobat, you get a stable, solid product that you can use to create PDF documents from scratch. Since it comes from the company that created the PDF format, it's safe to assume you're guaranteed compatibility with creating and editing documents that abide by the PDF standard.What needs fixing: The Edit Object tool wouldn't always select an entire row of text in some of the PDF documents that I used for the tests. For example, words that were underlined would be recognized by the application as a separate object, apart from the other words in the row, and had to be resized and dragged on their own.Product infoAdobe Acrobat X StandardAdobe Systems Inc.Price: $299Pros: Stable. From creator of PDF format.Cons: Expensive.Acrobat offers ways to get around this. For example, I could hold down the Shift key when selecting more than one body of text or multiple rows of text. I could also click and hold the left mouse button to drag a rectangle frame around all the text I wanted to merge together into a single graphical element that I could then resize and move.Bottom line: For many, $300 may feel like too much to spend to change words and graphics in PDF documents. It all boils down to paying more for an application that comes from the creator of the PDF format, so you know the company that sells the application will be around to support the software and update it with new versions in the coming years. If you need some of the additional features that come with the product and\/or have a business operation that handles a lot of PDF documents, then you might be interested in paying for the Adobe name and service.On the other hand, if all you want to do is edit text and graphics in PDF documents, you may want to look at one of the less expensive alternatives covered in this roundup.Foxit PDF Editor 2.2The free Foxit PDF reader is a lightweight alternative to Adobe's PDF reader. Foxit PDF Editor 2.2 carries on this tradition -- it lets you edit your existing PDF documents quickly and easily.User interface: When you load a PDF document, the page you're working on is displayed in the center of the application; any bookmarks the document contains are set in a column to the page's left; and the properties of the specific page being displayed -- or of the row of text you've selected -- appear in a right-hand column. This properties column shows stats such as the size of the page and, for the row of text selected, the font name, size and color, plus the row's position on the page.Working with PDFs: Text editing in Foxit works differently than it does in Adobe Acrobat X Standard.When you double-click on a row of text, the application switches to a new screen that displays the page and row you selected. You then position the cursor to the point where you want to enter or delete text. When you're finished with your edits, the application saves your edits and returns you to its main window, showing you your document once again but with your changes in place.When you select rows of words or a graphic, the selected area is surrounded by a rectangular border marked with eight anchor points. By clicking, holding and dragging any of these points, you can resize the height and width of the row of words or graphic.Unlike Acrobat, Foxit lets you change text height and width independently of one another. So if you want to, you can stretch or shrink the height or width of your text to the extreme. This feature may not be useful when editing formal documents, but it could be handy if you're changing a page where text is presented more as a design element.You can rotate text or images by clicking the center of the selected object, which turns the anchor points into arrows indicating clockwise\/counterclockwise and side-to-side directions.Product infoFoxit PDF Editor 2.2Foxit Corp.Price: $99Pros: Fast performance.Cons: Switches to new window for each edit. No thumbnail page previews.What works well: Foxit runs very quickly -- impressively so. I never felt slowed by performance issues.What needs fixing: Foxit switches to another screen for each line of text you want to edit, and then it switches back again when you're finished. As a result, if you have several lines of text to edit, it will switch back and forth each time, which I found very distracting. Also, unlike Acrobat, Foxit lacks thumbnail previews of pages to help you navigate through your document.Bottom line: Foxit PDF Editor 2.2's zippiness and surprisingly small installation file size (just over 4MB) make it ideal if you only need to make occasional changes to PDF documents, and especially if you're using an older or slower computer.Nitro PDF Professional 6Compared to Foxit's plain, basic appearance, Nitro PDF Professional 6 certainly looks prettier. It borrows from Microsoft Office 2010's "ribbon" interface: Tools are spread across the top in tabs with labels like "Create and Convert," "Insert and Edit" and "Review." You click a category tab and then choose from functions within that category that are represented by big, bright icons.User interface: Vertical tabs run along the left side of the document (listing "Pages," "Bookmarks," "Signatures" and so on). If you click the "Pages" tab, for example, a frame will open and show you thumbnails of the pages of your document to help you scroll through them.Furthering the tab interface motif, when you have more than one document loaded into the program, Nitro places each one under its own horizontal tab.Working with PDFs: To edit a row of words, you double-click on the row and a blinking cursor appears. You can then move that cursor along the row and position it where you need to type in or delete text.Nitro also lets you move, resize and otherwise manipulate text in a way that's similar to the way you do it in Foxit: If you click on a row of words, they will be surrounded by a frame marked with eight anchor points. You can then drag and drop the text row to another part of the document.Clicking on and dragging any of the anchor points lets you stretch or shrink the height or width of the text. Like Foxit, Nitro also lets you change the text's height and width separately; these two aspects are not linked together to maintain the scale of the text's size, as they are in Adobe Acrobat X.And there's a ninth anchor point set above the frame. When you click on and move it side to side with your mouse, you can rotate the selected row of text clockwise or counterclockwise.Nitro's tools for resizing or repositioning graphics in a PDF document work the same as its text tools.Product infoNitro PDF Professional 6Nitro PDF Inc.Price: $99.99Pros: Tab interface. Handles multiple documents well.Cons: Paused when saving edits.What works well: I liked the way Nitro handles multiple documents: You click on the tab of the document you want to switch to, like you do when clicking through the tabs of Web sites opened in a browser. This is a simple but useful feature that sets Nitro apart from the other three PDF editors in this roundup.What needs fixing: Nitro PDF Professional 6 ran well, generally. But as I finished editing, the application would pause briefly -- apparently to process the new text and incorporate it into the document -- before returning full control back to me.Bottom line: Nitro PDF Professional 6 is a good choice for people who like the Office 2010 ribbon interface, and its use of a tab interface will make editing among two or more open documents convenient.Nuance PDF Converter Professional 7Nuance Communications, the maker of PDF Converter Professional 7, is known best for its speech-recognition software, Dragon. PDF Converter uses editing tools that are nearly identical to those used in Adobe Acrobat.User interface: As is the case with the other PDF editors in this roundup, side panels accompany the document in the application's main viewing area: panels on the right side help you do things like sign the document digitally, set passwords for it and embed watermarks into it. A panel on the left lets you quickly navigate through the document's elements, such as its bookmarks, thumbnails of its pages and tags.Working with PDFs: Nuance's method of editing text in a PDF document is nearly identical to Acrobat's: You select a tool called Touchup Text and then you click the cursor on a spot in a row of words where you wish to enter new text, or you highlight words or letters you want to replace. Then you just type, and the new text will either be inserted at the point where the cursor is positioned or it will replace the text you highlighted.Like Foxit and Nitro, Nuance lets you alter the height, width and orientation of a row of text, and the height and the width can be changed independently of each other.However, while the other two applications use the same tool to edit and manipulate text, Nuance uses one tool, Touchup Text, to edit text and a different tool, Touchup Object, to manipulate blocks of text. It looks identical to Nitro's editing tool: Selected text is surrounded by a frame marked by eight anchor points, which you click on and drag to stretch or shrink the text row's height and width. A ninth anchor above the frame lets you rotate the row clockwise or counterclockwise.Even though Nuance (and Acrobat) separate the chores of editing text and manipulating it, I didn't necessarily find this inconvenient. In some ways, it helped make things clearer in my mind as to what exactly I wanted to do with the text (edit it or move it).Product infoNuance PDF Converter Professional 7Nuance Communications Inc.Price: $99.99Pros: Can split document into separate views.Cons: Loads a separate window for each document being edited.What works well: What makes Nuance different from the other three editors is that it lets you split your view of a document in the main window into two or four panels. Within each, you can scroll through and work on different areas of the same page. This feature can be useful if you need to work on a document with unusually large pages.What needs fixing: When you do load more than one document into Nuance, the program runs another window of itself -- so if you open three documents, you'll have three instances of the Nuance application running. Cutting and pasting text and graphics among multiple, open documents can feel like a juggling act, compared to Nitro's more efficient tabbed user interface.Bottom line: Nuance is a good low-cost version of Acrobat, and the split-screen view of your PDF can be helpful if you need to work on a document that has several pages.ConclusionsAdobe Acrobat X Standard is a premium product that works well, but its price makes it hard to justify if all you need to do is simply edit a few PDFs now and then.Nuance PDF Converter Professional 7 works well; it's basically a low-cost clone of Adobe's software with the addition of a split-screen viewing feature. However, it's awkward to work with when you're dealing with more than one document.I was initially partial to Foxit -- the great reputation of the company's PDF reader and its surprisingly small installation file size were strong factors in its favor. But Foxit turns out to be a bare-bones application when you compare its features with Nuance's and Nitro's, and I wasn't fond of its indirect way of letting you edit text. If it cost less, then it would be a far more competitive choice.So I have to give the nod to Nitro PDF Professional 6. For the same price as Foxit and Nuance, it's a nice balance between the editing tools of Acrobat and Nuance and the speed of Foxit. It has the most efficient user interface -- thanks to the fact that it uses browserlike tabs -- when it comes to editing text and manipulating images, especially when you need to cut and paste among multiple documents opened at the same time. And its use of an interface identical to that of Microsoft Office's ribbon interface means it can mesh well with your workflow, particularly if you are already using the latest versions of Office.In the end, the tabs win.Howard Wen reports on technology news, trends and products as a frequent contributor to Computerworld and Network World.