What a load of crap. We dont know if the prog is smt enabled, SSE2 enabled or HT enabled. Without a great deal of optimizations, the P4s are dead. Sure, the answer to the question is, for his needs he will never be able to tell the difference. He could probably have the same results with a new celeron. The slowdown of a few billionths of a second could easily be made up with LL ram, or a better nic card. Helll, the dew on the poles outside his house would have more impact.
The straight answer is, without better data, there is no right answer. Even the right answer is not going to do you any good. We are talking a difference of practically zero. The time lost sending the data to your nic card is more critical.
There may be a thousand ways to speed up your transactions, but the difference in high end chips is just not it.