The guys at the [H] are the latest to publish an article comparing the frame rates while gaming in XP versus Vista. They use an 8800GTS & a 7600GT to play games like BF2142 & Flight Simulator X, then lay out the frame rates in comparison tables. Take a wild guess as to which OS wins out...

"While some have reported no change in performance, we’ve seen poor driver support in Vista cause serious problems with performance and overall compatibility in various gaming titles."