i would use Ghz to determine the speed of the proccessor, but that doesn't really matter anyway considering this:
I have an Intel P4E chip running at 3.2 Ghz
An AMD chip running a much lower clock speed can totally put to shame my 3.2 Ghz P4E.
Look at the AMD chips like this, even though a 3200 AMD might perform like, or even outperform a 3.2 Intel P4, it's real clock speed is like, 2.?? Ghz.
I'm not sure of the real clock speeds of AMD chips, since I have only one comp running an AMD chip, that one happens to be a AMD Athlon XP 2400, which it's realy speed is 1.99Ghz, but, it performs or outperforms aN Intel 2.4 chip.
So, it's not the speed that matters, it's what the chips do with that speed.