Although once again it pains me to say this: ATI is better than Nvidia during those stages of cards. You'd be better with a ATI 9600 or so instead of that. The last series of cards ATI outperformed nvidia by quite a bit. with the newer cards 6800 and X800, its the opposite..nvidia owns ATI. So if I were you in this case Id look towards ATI, although I had a 256mb FX5700 and it ran great on games like Soldier of Fortune 2 on all high settings just fine. Don't know how it'd do on far cry or doom though =/
EDIT: Bah I always forget this. I was just informed today that sometime before the end of this year nvidia is to release a 6600GT (lowered down version of the 6800) and its 128mb DDR3 memory....it also outperforms the ati equivelant and will sell at about $199 I believe.