It is unusal for a fresh install to be slow.
Have you installed your chipset drivers?
Downloading drivers does not mean they automaticaly install,you should update ALL drivers Via device manager.
Could you test your RAM/Memory Via this link please.
Memory upgrades from Crucial.com - About Crucial:Media Toolbox
Could you check what speed your prosessor is running at in task manager?
20 gig hard drive?em how old is this hard drive?
Click start then on run type in box CHKDSK click ok.