If you're willing to spend ~$100 more than the q6600, intel is releasing their new line of quad cores on January 20th, and they are an entirely new technology. The Q9450 is going to be the mid-range one, and it has a 12mb cache on it (as opposed to 6mb on the Q6600) and is apparently going to be an overclockers dream.

I'm going to buy one of these puppies when they come out.