Digital photography and multi-tasking are just two reasons why I'd welcome signifcant improvements in power and speed.
...see post #18!!!!!!!! You are behind the times! (I have a G4 and am getting ready to get a G5!) iMovie, iPhoto, .Mac, are just a few of the reasones... and of course there is a variety of games!( Just no Microsoft Flight Simulator, without an emulator, which runs quite nicely and faster than most p4's)
I don't believe there are 64 bit apps for the Mac. There is a 64 bit beta for PC Photoshop.