E6600 at 3.2Ghz, and a single 8800 GTS 640.
Before the patch, I played through fine with all settings on high at 1680x1050.
When I got the 8800 GT I played through with the dx9 very high tweaks.
If you have to play at 1024x768 with a system like that. Something is wrong.
The only time did my fps really plummet was the very last level... and well you need a nuclear reactor to power the kind of computer needed to run the last level
Though I hear the patch makes the last part of the game run a lot smoother. I should play it again.