Anybody have any links or info concerning XP performance in games?

[Caveman]

I'm a serious flight simulation/game enthusiast that also does CAD, and other engineering apps. Looking to get a AMD Palamino soon and was wondering what type of operating system to get... 98 is supposed to run the fastest, right? Is XP a "bit slow" for someone concerned about every last frame/sec? I can tolerate a 3% drop but not much more -- will I be disappointed with XP performance.

If you have any links to reviews/tests, I'd be grateful if you posted them.

Thanks.