Call of Duty Modern Warfare 2 Lag On E8400/4850

Well as my title states I have a few lag issues with MW2

I can't play with anti-alalising or with the extra setting on textures etc or have soften smoke edges enabled... My Computer can surely do this right? I game at 1280x1024 most of the time. My computer can't be dated that much can it? I also tried upgrading drivers from 9.11 to 9.12 and that made it worse... tried the hotfix and the didn't work either... I tried the beta 10.2 drivers and they still lag but not as much.

Thanks for any help.