"Is a single 1.8 G5 comparatively faster or slower than a dual 1 G4?"
Duals only really "show their stuff" with apps that are designed to use them, like FCP. Still, I'd say that the 1.8 G5 would beat a dual 1 G4. But for FCP etc., always get a dual if you can. Also, make sure you get a machine with PCI-X. Some of the G5s don't have it.
- Justin Barham -