As far as 3D goes you'd be better off getting a Dual Xeon workstation. It's a lot faster than the G4's, and would probably save you a lot of time while rendering. If it's the same price as the G4's, I'd definetely go for the Xeon workstation.

But like others have said, if you wait, and look around, you might find something better. Good luck with your endeavors, and oh yeah, get Maya!