If they're using a whole new chip architecture for the new dual core processors then it will be exactly like trying to compare an AMD processor with a Sledgehammer/Winchester or what have you core that runs at 2.2ghz and a P4 that runs at 3.2ghz. The AMD in this case will give you better performance iirc. This particular example may not be entirely correct because it's been several months since I've seen my lovely 3500+ and I don't remember exactly if it outclassed a P4 3.2, but it outperformed a 2.8 quite handily in any case.

Anyway the point is the new chip architecture will quite possibly totally change things and the new chips probably run more efficiently than the old ones allowing them to run at a lower frequency and produce the same or better results.

I probably should have stayed out of this since I've been away from my baby for so long, but I'm sure you'll all forgive me and my point is still hopefully valid despite my outdated information.