Vista is cool and shiny but FPS in Games takes a huge Hit no matter how much Ram you have.Its because of extra Services Vista has to run compared to XP.
Google and you will find advise for Gamers to stay away from Vista for now.
Still not many softwares are available.
Some Drivers Issues still not addressed.Still no native proper Open GL support inspite of new drivers release.
With Vista im in a Fix. Installed on my Laptop but no graphic drivers for Intel 915 yet. Runs with hardware Acceleration disabled.So installed XP sp2 again and damn Happy..
Then dual booting PC with Vista ( 6600Gt ) and aero only to show someone. Personally using XP For Gaming.
If you are a professional 3D user stay away from Vista is what most of the gurus on Sites suggest.
Err Ubuntu 7 has better Candy effects than Vista, i dont understnad why will you want to shift to Vista if your productivity is hampered.
Use Vista if :-
1) Fps in Games is not a major issue.(FOr people who love every single FPS in games as hard earned cash stay with XP)
2)If you are not 3D designer and user , then use Vista, but for people who want it seriously stick with XP
3)For people who Surf and use Office Vista is good..
Personally i think i will make VISTA my main stream OS only when it has Service pack 1 released.