I deal heavily with macs at work. I'm the network admin at an advertising agency, and all my production people/artists swear by them. They all tell me though, that the G4 isnt that much faster then their trusty G3's. Just a prettier box. I will say one thing, the new G4's are a godsend, they are very easy to upgrade, and are actually modular, unlink their older brothers. And they take regular PCI cards just like any other computer.
I still love my PC though, but I've learned to adapt to this other race of people.....