The C2D era is the best overclocking era, but is not fascinating cause pretty much everybody can overclock it, but the one that I like it as a challege was the Northwood era, not everybody was able to overclock a 1.6GHz P4 to 2.4GHz. I overclocked a P2 from 300MHz to 450MHz, a P4 2.4B to 2.8, a Northwood from 3.4GHz to 3.73 (Not that much), then the Gallatin (P4EE) at 3.4GHz overclocked at 3.6GHz stable (It sucks) and now the Dothan which I overclocked from 2.26GHz to 2.6GHz (Not bad but not great either, seems that this core hits a wall at 2.6GHz)