One thing to consider, the P4 will not burn up if it overheats, it just throttles itself back to use less power, and obviously gets a lot slower. Tom's Hardware had an interesting test a while back where they removed the heatsink from a P3, P4, and several AMD processors. The AMD's went up in smoke, and one took the MB with it, the P3 crashed but was not damaged, and the P4 didn't miss a beat, just slowed way down to prevent overheating. It was a pretty impressive performance.
