Despite Win2k and NT4 kinda having a rep for not for gaming, I found that most games actually did run on them fine. Especially Win2k, probably the most underrated OS of all time in the Windows lineup.
Really I think it got that rep mostly from people trying to run DOS games or shoddy ports from DOS to early Windows that still relied on a bunch of DOS stuff.
But Windows 2000 was much better for gaming. NT4 supported DX3 and DX5 unnoficially'.
W2k had a DLL call flag to enable a Windows XP like compat mode:
http://www.activewin.com/tips/win2000/1/2000_tips_43.shtml
It only worked on desktop shortcuts, but enough to run most quirky Win95/98 games.