The Intel Core 2 Duo series (I can speak for the Conroe core especially) has good over clocking potential. I have a Core 2 Duo E6600 that runs at 2.4 ghz stock, and I have it over clocked to 3.0 ghz with an after market fan. It's running without problems. Over clocking your CPU can be a cost efficient way to get more power out of components you already have. Over clocking isn't for everyone, but it's an option that's available.