AMD has an Integrated Memory Controller, which give AMD cpus soooo much memory bandwidth its not even funny. But you see, in real world applications, nothing uses that much bandwidth. But it helps none the less. AMD has just started to move other to DDR2 with their new flagship AM2 socket.
Intel on the other hand, doesnt have an IMC so they use the northbridge as the memory controller. The cpu and the northbridge talk with the FSB (front side bus) Though not as much memory bandwidth as the IMC, it works very well. The latency isnt that far behind the Athlon 64 on AM2. Intels usually have a higher clock speed and with the release of Conroe, they are very energy efficient. Conroe will soon turn the tide in gaming or it already has.