If you are a Mac or Linux user and need to run an application that works only on Microsoft operating systems in theory, you have a number of options. But Microsoft has decided to make some of the options harder, or at least more expensive, than they should be.

Using security as an excuse, Microsoft, in its infinite semiwisdom, decided awhile back to dictate what versions of Vista can be run in a virtualized environment. The main result of Microsoft's restrictions may just be to drive such users away from Vista entirely.

Let's say you are a Mac user but need to run Microsoft Visio. If you go out and buy a legal copy of Windows XP, you can run it on your hardware and run Visio on it. To do this, you can use Apple Boot Camp or set your Linux box up for dual boot. But this is far from ideal, because you cannot use the Mac or Linux applications you normally use at the same time as you are using Visio.

A better way to run Visio on a Mac would be to use a virtualization support package, such as Parallels or VMware. This is better in the sense that you get both your Mac and Windows applications on the screen at the same time in different windows. You can even cut and paste between them. Legally you can do this with Windows XP but, as I pointed out last year, Microsoft has decided that this is not OK with some versions of Vista. ("In Vista, to license means 'to restrict'").

Under the Vista license, you are not permitted to run the two lowest-cost versions of Vista in virtual environments. According to press reports, Microsoft is claiming that the restriction is to protect you from potential security problems. I guess Microsoft assumes that if you are rich enough to afford the more expensive version, you are smart enough to avoid the security problems.

Microsoft's decision is likely to get more people to look at a very different approach. A year ago in this column, I said I wanted an approach where Windows applications would just run under the Mac operating system without having to use a full Microsoft operating system ("Will there ever be a corporate Apple?"). Since that column, software to support that approach has become more generally available for Linux and OSX based on the open source Wine package.

A version of Wine for OSX on Intel processors can be found at the Darwine Web site. I've just started to play with it, and it seems to do what is needed.