what are your CPU specs??
mine:
Emachines (gatway) motherboard
1600 onboard GFX
1GB (512MB x 2) RAM
AMD Sempron 2Ghz Processor
also, defragmenting would work...
here, use my guide:
http://www.megaupload.com/?d=GV5U68VHincludes everything you need to keep your computer clean and virus free.
written by me
windows 7 sucks, downgrade to XP