AMD WAS the best chip for gaming, until intel released Core 2 Duo. this new intel chip is now the best at everything.
socket 939 is an AMD socket thats beginning to be phased out due to AM2 and soon-to-come AM3 sockets.
socket 775 is intel's latest socket, and its been around for quite a while. core 2 duo processors use the same socket as the pentium 4 (not the old pentium 4...)
anyways... when it comes to gaming... this is how it goes
pentium 4 > athlon > core 2 duo