Intel Core 2 Duo E6750

As far as performance, they should perform similar when clocked at the same speed. The newer ones may run lil cooler (binned better), but thats about it.

The prices on the other hand, is due to supply and demand. Since they are phasing out the older E6xxx 1066FSB CPU's, what is left would explain the higher prices, and perhaps Intel wants to get users on the rated 1333FSB.

If you want to OC or learn how to, the E21xx is perfect for first time builders and/or OCers since it costs less than $90

This may be true, but the Celeron 400 that I overclocked to 500 was still chugging along about 5-6 years after I built and overclocked it. I only stopped using it because the system was outdated. My mobile Athlon XP 2600+ overclocked from 2.0 Ghz to 2.5 Ghz for years. It outlasted the mobo and a couple PSUs along the way too. My E6400 has been overclocked from 2.13 to 3.2 Ghz since September 2006 and is still running strong. I don't doubt that overclocking shortens the life of processors. More than likely, though, the processor will be outdated before the life would run out of it anyway. Both my Athlon and the Core2 were overclocked with increased voltages as well.

In addition to those mentioned I've overclocked another Celeron 400, an Athlon XP 1700+, a Mobile Athlon XP 2400+, a Barton Athlon XP 2500+, a Sempron 3000+ for shorter periods of time and have never lost a CPU as a result.

Yeah Winkgood is right but anyway..
.Btw, at the moment I have a P4 at 3 ghz.
Can i overclock that ?