please remove all those inspid question marks in the subject line.
yes, performance is lower in Vista than it is in XP. However, this is mostly a driver issue. if gaming performance is absolutely paramount to you, wait until the ForceWare drivers have matured (2 months maybe?)
but since the GTS and GTX are so powerful, the drop in performance probably isn't noticable in MOST games. the exception would be oblivion and other demanding games. games like Quake 4, Prey, HL2/Episode 1, FEAR, etc... you will not see a difference in performance because the average frame rates are still well above 60fps.
I can tell you that I have the 8800GTX and the Nforce 680 chipset mainboard (Striker Extreme)
All the games are running worse in Vista with the beta-drivers from Nvidia...
In WinXP.. I always set these games at res. 1600x1200 with everything maxed out... and it runs great there... only in Oblivion I set it @ High detail instead of Ultra high because that game is too heavy even for my configuration..
My experience with games in vista (res. 1600x1200, all maxed out.. except Oblivion):
Oblivion: Almost unplayable
Quake 4: Crashes during loading (single player game)
Doom 3: Runs ok, but not as good as in WinXP (it's noticable)
F.E.A.R.: Runs when walking indoor area but absolutely runs like **** when entering outdoor locations....
Call of Duty 2: I got a white screen when starting a game... I hear the sound but no picture..
So you can say You'd better stick with WinXP when playing at the highest resolutions with the highest settings... but when playing with lower settings and res.. It will work fine woth Vista I quess...
Ok.. I have to be honest here... It turned out that I had the wrong Nvidia driver version installed (100.54).. I now installed the newest Beta driver (100.59) and the games written above work fine now... I almost see no difference with XP... Quake 4 now works... but there I can see that the game runs a little bit slower... So even with the beta-drivers.. gaming in vista isn't that bad
So sorry for the wrong info