I'm running an Intel Core 2 Duo 3.0 GHZ
8GB RAM
MSI Radeon HD 6950 2GB RAM
My game, and my wife's, who has an identical setup, runs great. No issues at all, getting over 70 fps.
Make sure you're updated the motherboard's BIOs, the chipset drivers for the motherboard. Also maybe there's something wrong with your install, if you continue to have problems, try reinstalling.