I am runnning XP on my work laptop, Vista Enterprise on my home laptop, Vista Ultimate on the kids desktop, XP Home on the GF desktop.
In all I have had issues with some of the software running fine on XP but keeps crashing on Vista. I'll stick with XP for a while as a backup while smaller companies start porting their apps to Windows 7.
At work we are by-passing Vista altogether and will go from XP Pro to Windows 7 just a bit after SP1 is released.
I guess the corporate world has an attitude entirely different than gamers, as graphics are not a priority, but legacy support is paramount.