The Core2 beats out P4 mainly because of the fact that Core2 CPUs actually have 2 cores, whereas a P4 even touted as "Dual-Core" is in fact, a single-core CPU that tricks the OS into thinking that it has 2 cores. My girlfriend's new computer that I built has a 2.8GHz Core2, and I have a P4 Dual-Core 3.2GHz (OC to 3.5GHz), and hers beats mine every step of the way. Gaming, Vista rating, everything.
Of course, you could spend an extra $50 or so and get a Core2 Quad, same idea as the P4 as it tricks the OS into thinking it has more cores, but this time it thinks it has 4 instead of 2 😛