[link|http://arstechnica.com/reviews/hardware/imac-coreduo.ars/6|iMac 17" Core Duo]
the [Rosetta] performance of the iMac Core Duo seemed to be on par with a 1GHz Power Macintosh G4
That's twice as fast as he's used to now - plus the G4 they're talking about would have had a faster bus than his system with the upgraded CPU.