Elmer, Re: I recently bought an Intel 2.4GHz P4 and it has very little overclockability, I was unlucky. I would think 2.4GHz is very near the bottom of the speed distribution, if not below it.
You bought the 533MHz FSB version, did you not? It's quite possible that your part could have been left over from B-Stepping inventory. The 2.4C GHz Pentium 4 chips tend to have a lot of headroom, given that they are based on a much newer stepping.