Video card is your main issue.

I have a 8800GTS (640MB) running 3 O.K. Main is 45fps, other 2 are 15fps details low.

I bought Kingston - 8500 - 1066mhz 2gb. Instead of the 4gb 667 i had, and the difference is noticeable.

I also have a Q6600.


Wait a few weeks for the 8900 to become available and you won't regret it.