I'm running an NF7-S mobo/Athlon XP2400 processor with Windows 2000.
A couple of years ago I upgraded the memory to 2GB - I believe your spec is only 1GB. Going up to 2GB on your PC will make a massive difference to the way games play on your PC. I can't stress this enough. If you have enough memory to avoid disk swapping games run an order of magnitude better.
I put in an AGP factory overclocked 7600GT a while ago.
Finally I upgraded my disk drives to 320GB jobbies, last year.
With this setup I can play WoW, Lotro at very high resolutions - much better than you might expect. Oblivion is fine. Clearly I am not geting the silly frame rates a bang up to date PC would give but for Oblivion for instance, around town and in dungeons, I am at high thirties, out in the wild it drops a bit mostly due to grass, but it is almost always a playable 20+ (turning grass on and off to suit the occasion is a trivial thing in oblivion).
Games that are fine with no caveats, and I'm looking at a pile in the corner of my room right now, include CIV IV, Homeworld I, Pax Imperia, Diablo II, The three Kohan games, Sid Meier's Railroads, Temple of elemental evil, Conquest (a Ubisoft space game), American Conquest, Empire Earth II, Emperor battle for Dune, Majesty, Dungeon Keeper II, Imperium Galactica II, The GalCiv series, Space Empires IV, Darwinia, Command and conquer generals series, C&C Tiberian Sun, Rise of Nations series, Total War series and Masters of Orion series (except III which is poo). I have played Unreal Tounament (II?) but it's not really my type of game.
But really, as people have said, practically anything about which is not too up to date should fly on your PC if you put more memory and a MAYBE a decent(ish) cheap(ish) modern low(ish)-power grahics card in there