Well for starters this is impossible for any CPU not running on LN2 or something similar, your CPU would melt with this much voltage, plus no motherboard can give that kind of vcore without a vmod (and even then I don't know if it's possible).
Therefore I'd like to say that you don't believe anything else you get from that program, I assume by maximum clock they mean the architectural limit of core either caused either by the FSB limited by the motherboard or the actual core limit itself. An Athlon XP would have a hard time getting 1GHz either way, even with LN2 or something similar.
It is even on AMD's website. The AMD model ##'s have nothing to do with intel's clock speed. A 2.8ghz P4 would kill the XP in a benchmark. So they are not equal.
Of course the Intel is going to excel in certain areas, no one is suggesting they are EXACTLY the same. The 2800+ will perform about the same as a 2.8Ghz P4 though, and that is
was the rating system was established for.