i just upgraded my motherboard and processor and am still getting low fps(30-40) while playing on medium settings.
windows 7 home premium
a880gz motherboard
amd athlon 2 x3 450 processor 3200 mhz 3 cores
4gb ram
gtx 460 1gb
Yeah, my cousin has a GTX 460. He gets similar FPS to you, there isn't anything you can do aside from upgrading your video card. It was good a few years ago, but its now low end.