That's exactly the behavior that I saw in the AMD based computers I built. The few that I finally got cooled enough (and I used the paste, the copper heat sinks, plenum, etc) were too noisy for their work environments.
Ok... lets. I'm not that familiar with AMD products anymore, so lets hear comparisons between top of the line processors from each. For instance:
This data may be a little old, but the P4 smokes the AMD in all but one test:
and this page has some interesting info too:
It looks like the Prescott would be faster the the Opteron due to the large cache size and it's HT.