I have yet to see a performance difference in games between xp and W2K, I am personally running W2K on all of my machines and love it, buddy has xp pro with a near clone system to mine and there was no performance difference in games at all that I saw. I am running 2000 pro just for info, and I have actually encountered odd errors and strange crap after installing the 3rd update pack for W2K. Also the updates made no difference in performance, just makes your comp safer, but with a hardware and software firewall I am good for now