I have a i7 920, 8GB RAM and an ATI 5870 vid card.
Game runs great and looks great set to "High" display settings, but when trying "Ultra" the framerate drops and game performance is poor.
Have any of you tried this program and is it any good? A guildie of mine swears by it:

http://www.iobit.com/gamebooster.html

If you have tons of other programs or just other backround stuff running, its amazing. you can go from 30 fps to 60-70. Yes it is safe and it works just fine