I can't comment directly on comparrisons with the new Intel i7 chips, but I can tell you what I learned from comparrisons between identical clock speed AMD and Intel CPUs prior to the i7 which I did for my work.

In short, the AMD performed computations between 5% and 10% slower than the Intel. But the AMD more than made up for this in memory performance, as the memory read/write performance was from 33% to 50% better than the Intel. Hypertransport and that on-chip memory controller of the AMD chip appeared to be the difference.

I understand that the Intel i7 chips now have the memory controller in the CPU as well, but the few things I've read on the matter indicate that it reduced the gap but hasn't yet closed it.