Just built PC for my brother to play CoD4 with me and various other games (oblivion, hellgate, overloard, the witcher, C&C3, Unreal 3, Quake Enemy Territory... the list goes on)
Anyways here's what it consists of:
OCZ 610w PSU
GA P35 DS3L
E2180 OC @ 3.0
Evga 8600GT 256mb
2x1gb ddr2 800 (G.Skill)
250gb wd hdd (sata)
sata dvd read/write (no lite scribe)
He had keyboard, case (my old one), mouse, and monitor... total for that with shipping from new egg was like $500.
With the extra $200 or so I could have gotten better video card 8800 or so, also could have included monitor in the price for that cost level. Didn't need to buy XP as I had an extra copy from an old computer, but could have afforded that... or nice keyboard/mouse... lots of options available for the extra money... but for $500 that PC rocks hard and plays most games with no problems whatsoever (we don't mind turning down settings) and his resolution is only 1280x1024 anyway, so the 8600 is fine.