Let me get in a plug for an underrated cooler. I got the Rosewill RCX-Z775-EX at a good price bundled with a Q6600. It uses a quiet 92mm fan and is smaller and lighter than the big dogs, but it definitely does the job.
I'm at 3.5ghz, idling at 36-38c and running 58-62 with all four cores loaded to the max. That's on an Abit IP35.
It's a bolt-on unit with a quality look and feel. Works with Abit's bios speed and heat controls. Unless you're shooting for the sky on your overclock, it's worth considering.