I work as a computer tech
Vista does have alot of quirky issues, such as major updates like sp1 causing errors with applications and never competing.
I guess the general terms applies, if it ain't broke don't fix it. Personally i still recommend people xp, most of the good applications still run on windows 2000.
This is just a sign of how long most applications will continue to support xp, even tho vista is being pushed on the market level.
The way i see it (people will differ)
Stability comes first, then performance.
Xp has long proved its self, so it should be used majority.
The only thing i would switch to vista in the future would be for DirectX 10.