What exactly do you mean?
For all intents and purposes, the G5 is better than a G4 and G3, and a G4 is better than a G3.
If you mean is it worth investing in an older Mac to make it better, versus buying a new one, then often upgrades are a good move.
TheGimp said:
Which is better, a G4 or a G5? Or a G3 with an iMic?