Well, I've got a couple older PC's lying around that other people in the family use, but discounting those...
I've got me old 900 mhz Celeron with a Geforce 2 MX 400...
My newer Sony VAIO 2.6 GHz Pentium 4 with a 128 MB Geforce FX 5200
My PowerBook Pismo G3 500 mhz
And my newer PowerBook G4 12" 1 GHz w/Geforce FX 5200. They just bumped the speed to 1.25, too
The PowerBook is a sweet machine
All PC's running Winblows XP. I just hacked my Start button this morning to show a pic of Bill Gates of Borg instead of the windows logo.