A slight drop in the usage of Microsoft Internet Explorer and a new release of the open-source-based Netscape browser shows that Microsoft's dominance of the browser market is not complete - and may be slipping.\u00a0Netscape Navigator 7.2 is based on Version 1.7 of the Mozilla Web browser - the open-source browser used as the default on many Linux PCs and workstations. Improvements in the Mozilla-based Netscape software include integration with AOL Instant Messenger as well as tabbed Web browsing, which allows for multiple Web pages to be open in one browser window - similar to the Opera Web browser.Microsoft recently lost a little ground to Mozilla, as its market share dropped from around 95% to 94%. Meanwhile, Mozilla saw its user base increase by a more than one-fourth, capturing about 3% of the market, according to WebSideStory.com, which tracks Web usage statistics.Some observers say the growth in Mozilla usage is attributed to security flaws in Internet Explorer. Others say the Mozilla software has just gotten better and is more attractive to users than before.\u00a0IDC predicts that the use of Linux on the desktop will increase from around 3% presently to more than 6% of the market by 2007, surpassing Apple Macintosh as the second-most-used PC operating system. With this rise in open-source PC software, you might also expect to see Mozilla's Web browser share grow as well.