The 450 and 500 G4's have a re-designed logic board, the 400's have the G3 logic board, I think (emphasize I think) the new logic board takes advantage of the G4's AltiVec technology(what makes it a super computer) anyway everyone I know who knows anything about macs says to get the 450 or the 500. but you can't get the 500's yet.(posted 8940 days ago)