Narrowed it down to 3

[TriEclipse]

You can get a E6300 to 2.6Ghz on stock cooling. Higher than that, you'd need to up the voltage, so a better heatsink would be required. You could get the E6300, and the best air cooling heatsink, and still save money over the E6600.

 

[Sora]

Listen UT, Just make sure your case has a couple fans. Most people suggest 2x120mm Front and back fans for pretty good cooling. Keep the stock HS&F on the CPU and OC it up to as far as without increasing voltage. Even if you dont have that many fans (most decent cases have at least 1 120mm) it will be fine. Trust us when we tell you, that you will have no problems reaching those speeds