I'm going to upgrade my 1.6ghz to a 2.4, 2.53, or 2.66 (anything higher is a little pricey hehe) with some extra money I have. Which one should I get that yields a better overclock with air cooling? Oh and also, what kind of HSF solution should I get (besides the SLK-900u that won't clear my mobo). Thanks for your posts. 