I have used Performance Test in the past and really liked it. It tests every aspect of the PC. It is free to try and you will be able to run both PC'* and compare the scores in the various catagories. Here is the link:
Question, is the new PC "fresh," and what graphics cards are there (or at least the onboard chip). Chances are the benchmark program did graphics, so a big difference in those will produce different scores. Also, depending on your socket for the AMD, you can upgrade processors to something way faster than the P4 for around $100.
I would have for sure said the Intel would be faster but not by much. If you wanted to go faster you should have just got some good OC memory and OC'd the AMD. I will state that the fastest computer I build so far was an AMD 3500+ with 1gb of Mushkin memory and Blitz chips on it. Somehow it is faster in every way, and as far as I can tell it'* the memory.