A year ago, a dual 2 Ghz PowerPC processor machine was half again as fast as a dual 3.6 Ghz Intel machine.
But now a single 2.1 Ghz PowerPC processor machine is half the speed of a dual 2 Ghz Intel machine.
Assuming that two processors offer a 20% speed increase over one and that a 3.6 Ghz pentium processor is twice as fast a 2.0 Ghz pentium processor (ref Tom's Hardware), it appears that CPU benchmarks run almost four times faster under OSX than under XP.
Either that or someone's cooking the books. Apple really ought to take down that first page.