Hmm I also have a desktop with a quad core amd OC to 3.8ghz, nvidia 1gb video (forget model about 2 years old though) and 8 gb ram that does the same 10-20 fps. btw on both computers the fps meter is green which was video card to my understanding?
edit: remoted to pc to get video card model. nvidia geforce gt 9600 Not a great card by any means but has ran games like rage and bf3 (yes i know they are fps games) at high/highest settings