My 450MHz PIII running windows Me could rip and encode a CD (60 minute) in around 90 minutes.
My 400MHz iMac could rip and encode the same CD while playing it back, and would have finished after 20 minutes.
I know there's a lot of other stuff going on to consider (Mac OS 9 being the obvious factor, no preemptiveness going on) but it's still a hell of an improvement...