Athlon XP (32 bit, but ahead of the T-Bird) 2800+
512 MB DDR
FX 5700 Ultra (softmod QuadroFX 1100)

For Maya that's all I really need. Now -- if you are going to run games... don't bother buying a new graphics card -- UE3 is going to toast all but the cream of the computer crop. (3.2 GHz is considered a "low end system" according to Tim Sweenie)

Did you mention you're NOT running games on it, and its for 3d Modelling? Games must keep at least 24 FPS (although some people seem to think 60FPS is bare minimum, others 30, etc.) -- so if you are pulling 3 FPS it just won't work. Maya on the other hand -- 1 minute/frame... 4 minutes? 10? 2 seconds? Who cares -- its all what you're willing to sit and waste.

If you want to do yourself a favour and don't plan on playing games past 2004 -- pick up a FX or a GeForce 4 CHEAP (say -- 20$ cheap) and then softmod it Quadro... it'll do you better than a 6800 in GeForce mode and will cost a HELL of a lot less...

If you want to play new games... yer screwed then :p