If you didnt do a full reinstall of win 7 you shouldent have to. I just had a similar issue. I swapped out a mobo and would get ok frame rates except for when I would turn with my mouse. I went here.http://www.howtogeek.com/howto/windows-vista/remove-old-drivers-after-upgrading-to-new-hardware/
It shows you how to find hidden drivers.
I deleted EVERY driver that was grey and not being used.
My system is now smooth as can be.
Hope it helps