My personal experience with Win2k gaming has been very positive.
The only game I haven't been able to play has been half-life. Pretty much everything else I'm interested in plays, and plays better than it ever did in any version of win 9.x
I don't bother with benchmarking since I stopped o/c'ing. Its no big deal to lose a bit of framerate, when the games no longer crash, don't jitter or lag (well Messiah shouldn't count because it was broken in any OS), and generally run smooth as butter.
This isn't with a balls to the wall system either, just a middle of the road one. Granted I do have a lot of memory, and even when I insist memory is one of the most important pieces of hardware on message boards, people tend to scoff at the idea. Then again, those people seem to be the one's with the most problems :-)
Case in point, I was playing Motocross Madness 2 in 1920x1440x16 the other day with about 15-17fps. Almost playable and this was with a TNT2 Ultra. How many people with win9.x can do the same thing?
Its a personal preference, but to me Win2k is the best OS for everything I do with a computer.