Gamers are crazy about CPU/Memory upgrades, and push every new CPU to its limit by overclocking it if possible. I am typing this on a 1.8G C2D overclocked to over 3.0G, and I am doing this not because I want to type faster, but to squeeze few more fps out of cpu/gpu combo. I am not a heavy gamer but still I upgrade my CPU every 6-12 mo or just try to keep up with friends playing online.
Both AMD and Intel are trying hard to make their CPU better for PC games.