For one thing it has a 1600 Mhz Front Side Bus compared to the 800 Mhz of a P4. It has more sockets (therefore it can transmit more data, in less time), it is 64 bit (will make a huge difference once the applications are released). And it has a much shorter pipeline than the P4. AMDs are also better at multitasking.
There are also many more advantages that I am unaware of, so I just listed what I know. I have always been an intel guy, but I decided to go with AMD for my next gaming system.