click on porperties after right clicking on c: drive and defrag the harddrive. then download spybot search and destroy and run that. then run ad-aware again, make sure youi have all the updates. delete any crap on your computer that shouldnt be there. if you want you could try getting more ram. since newer programs use more ram as a minimum nowadays compared to 2 years ago.
AMD 3000+ @ 2.25
Corsair Twinx 1024mb 2x512mb XMS
MSI 6600GT's SLIed @ 565/1100
Neo 4 Platinum SLI Mobo