No, OS will indeed be important. You wouldn't want to recommend 2gb RAM to someone running a gaming PC on a vista or win7 system now would you?
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.