well, its a great processor. It comes at 2.66gz and can be overclocked quite well... however the e8400's are on newegg as of like, yesterday, so that would be the route to go.
its only like 30ish bucks mroe (not sure what the e6750 is at now b/c of the new releases).
but anyways, the new 8400's are made with the 45nm technology and not the 65 that the 6750 and 6600 are using. This usually translates to higher speeds
the 8400 comes 3.0ghz stock, and though i dont know of any1 that has it yet, i can imiagine giving the performance of the other intel chips that this will OC amazingly well.