I think to compare a PC processor to a Mac process you have to almost double the speed. Like a 1Ghz G4 would be about a 1.8Ghz P4. I know in a Keynote Steve Jobs calls it the "MHz myth". I think they compared a 867Mhz G4 to a 1.8 Ghz P4, and said that the G4 was about 50% than the P4 at the same task.