Opening projects on new blender install

I have a problem with all of my blender projects. I copied all of my blender projects onto another hdd and them reinstalled windows. After that I installed Python33 and Blender 2.66 and now after I copied my projects back to my primary hdd every single one runs really slow! I had an fps game I was working on that ran 60fps all the time before I formatted. Now it runs at like 47 and some times 20fps!! Why does this happen? Its not the first time either! I tried appending to a new scene and same thing happens!
Thanks!

If you have reinstalled your OS, ensure your graphics card drivers are up to date.

Fixed it! Wow I feel dumb…I forgot about graphics drivers. Thanks!!!