I think so. I'm using it on a six year old 533MHz Dual G4 "Digital Audio" with 1GB RAM. But my projects are not VERY big, and i don't use it for first-class rendering. Artlantis R is quite OK though.
The Duality of this machine helps a lot. And a decent graphics card (I've got a Radeon 9000Pro with 128 MB VRAM) helps with Open GL rotation. Those cards come cheap these days.
But if you intend to use it on a Powerbook, I think you might swear. The 400MHz powerbooks had slow hard disks, and the graphics of that time wasn't very good either by today's standard. I'd much rather just buy a MacMini. Today's models are cheap and comparably fast, or you should be able to grab last year's G4 model used for a small sum. They also had good enough graphics.
(And, I've placed an order for a MBP C2D, but don't tell anyone!)
AC4.1-AC26SWE; MacOS13.5.1; MP5,1+MBP16,1
