I've lost count of how many time I've heard people say "I installed Vista, but I'm back to XP now". People who know enough to be comfortable with rebuilding their own systems of course, one wonders how many of the general population would do the same if they knew how.
I'm going one step further now... today I received a free VMware Workstation 6 key (being a VCP and all), and I redeemed it for the Linux version of Workstation. I'll keep a disk around with XP on it for when Team Fortress 2 comes out, but otherwise I'm sure any other app I'd care to use (that doesn't have a Linux equivalent) will run fine within a VM... Visual Studio 2005 is about the only one I can think of in that category to be honest!