Win2k... and who cares if you play games or not... if the game is older than 4 years, then it might have problem. But with Win2k, i haven't had a SINGLE game problem yet. This include games like Everquest, Asheron's Call, Diablo 2, Rainbow Six and Rogue Spear, Age of Empires 2, Deus Ex, Balder Gate 2, UT, Q3... and a half dozen other games i cant' remember right now.
Just make sure your hardware is compatible with Win2k... if everythign checks out, then go for it.