I don't know if anybody pointed this out yet, but:
VIDEO EDITING DOES NOT RELY ON THE VIDEO CARD! I don't know where people get these ideas, but I keep seeing the misconception iggyb repeats here. Editing video relies on bus speed, drive speed, and the main processors. Photoshop, for the most part, does not rely on the GPU to process its filters and effects. I'm not sure about the relationship between GPUs and 3D graphics rendering beyond how important they are for games, but I do know that with some very few exceptions, the GPU is not used for film or even video-level 3D rendering. One exception is the Balrog from Fellowship of the Ring: the fire effects were animated sprites mapped to a 3D structure and animated in realtime using an ATi card. It's in Cinefex if anyone wants to track it down.
3D hardware accelerates two things: games and QuartzExtreme.
Sorry about the rant, but I got tired of seeing this. You know what: for all of you fence sitters, if you bought the machine, you'd be the happiest Mac user on the planet. My 1.6 GHz G5 hasn't let me down yet, and it's long in the tooth (how?) and "crippled."
Yes, I'm an apologist. But I'm also a realist: does it do what you need? Yes? Then get it and stop complaining about things you don't understand.