basic setup should be a 2.4 quad intel, 2.6 amd. 2 gigs minimum or ram if your running win 7 or vista. 4 would be better but wont have much of an impact on the game but will help the o.s.
9800gt or hd 4850 for medium or better gfx @1280/720 to max out the game you will need 1.5 gigs of ram and a gtx260 similar performing gpu.