yeah how much ram do you have? also how many programs are running in the background? those take up alot of system resources.
go to the start menu and click run and in the box type "msconfig" and click the startup tab. how many programs are starting up?
it could be a combination of things
ASUS A8V Deluxe MOBO rev 2
AMD Athlon64 3500+ 90nm Winchester Core,OC'd @2.6ghz
PNY-Geforce 6800gt, OC@ 420/1.15
2x512MB Corsair Xms Xpert XL pc3200 2-2-2-5
2xWestern Digital Raptors 1-36.7G 1-74G 10,000 RPM HD/ 1x 160gb maxtor
Im water cooled now with swiftech mcw6002 and dangerden maze 4