firstly, Intel's 64-bit Pentium 4's actually emulate 64-bit
they can only process 32-bit code, but software-wise they can emulate it. this is much slower than Athlon 64's natural 64-bit processing
I'm not saying it isn't fast at all though, I mean it's fast, but only really good for apps that can run dual cores. mostly server-type apps, where you may as well be using one or more Opterons or Xeons
for gaming, AMD has hit it right on the head in terms of power, gaming performance, price and even compatibility - when I say compatibility, I mean they have support for more instruction sets than Intel's.