Why? Because I don’t believe the Linux desktop will ever go mainstream in the “developed” nations of North America and Western Europe. We just have too much experience with Windows. The benefits of moving off Windows (or, in my case, the Mac) are outweighed by the costs. Not dollars-and-cents costs, but productivity costs. It’s not worth $400 to me to switch to an experience that doesn’t work nearly as well (especially since I can get my applications as open source, like OpenOffice, Handbrake, Adium, etc.).
Funny you should mention that. I recently tried to switch my old Dell laptop back from Linux to Windows. My primary laptop is Linux but I found I needed a Windows desktop for testing the binary versions of the APP Test Client. Anyway, tried is the operative word, as I had misplaced the original Dell disks and tried to use a full off the shelf version of Windows XP Pro, which completely and utterly failed to find ethernet and wi-fi drivers. Of course, failing to find those drivers means that I would have to find, download and burn those drivers onto a CD on another computer to load them onto the Dell. This is the same machine that I installed Ubuntu onto over a year ago, and back then Ubuntu effortlessly found drivers for the both ethernet and wi-fi during the initial install. Compare that to the Vista experience and we may be reaching a tipping point, at least as far as drivers are concerned.
Oh yeah, as for Windows, I eventually gave up and installed TightVNC on my kids Windows desktop and used that remotely from Linux.