I'm sorry nobody from the community hasn't responded to your question yet. I will try to give you a little bit of an answer here.
From what I've heard the WUs are designed around Intel processors so generally Intels perform a little better than the AMD processors. Not to say that a high end AMD won't still beat a P4, but with midstream processors the intels work a little better.
If you run the F@H client and run the -verbosity 9 command switch you will be able to see your benchmark result for your processor in your FAH log. You can check with others to see how your PC compairs to thiers.