Have you tried updating Windows and/or your graphics driver?
Windows 7 Service Pack 1 has been out for some time.
Only the SP1 Release Candidate is out, not the final version. (I installed the RC version on my secondary PC just for fun, but I didn't notice any differences for good or ill.) The RC should be pretty stable, though, so it might be worth a shot. I just wanted to warn you that it's not final software yet.