slow windows exploror

Hi Guys, I have pretty good pc specs and for the life of me, I just cannot understand why my pc is not flying. I also contacted my ISP and told them I was on 10 MB and if my modem was getting too old for the specs I have now. They are not fantastice , but ok. Here they are.

Specs :
HD 200 GIG
CPU ; SOCKET 754 AMD ATHLON 64 3000+ Processor
MB : Asus K8V SE Delux
Graphics : ATI Radion x1950 Pro
RAM : 1.5 Gig
Soundblaster Audigy
Hyper 580 PSU
ISP Speed : 10 MB

I have done all the things I believe you do to check it out, ie , Antivirus check, malware, trojens, registry cleanner, and defrag.

I would appreciatte any comments anyone might have.
Thank you.