One last question...
Has your system been reformatted in the past year or two? It's entirely possible that you've just got far too many background processes running from too much miscellaneous crap installed on the system.
Opteron 175 @ 2.83ghz
2GB DDR 400 @ 333 CAS 2-2-2
2x80gb sata2 drives RAID0 for audio editing and OS
1x120gb IDE drive storage
MSI k8n Diamond Plus
M-Audio Fast Track Ultra
19" flat CRT (Monstrously heavy monitor)
I use Blender, Ableton Live, GIMP, AND play games on this thing. Shove your resource intensive operating systems.