Lot’s of good posts here. Rather than get into the debate, I’ll post my thoughts and experiences.
First, overclocking can become an obsession. It’s a gas. If you are good, you can tweak out a CPU to within a few MHz of it’s maximum. Bare in mind, if you are at the edge, a minor change in ambient temperature will change your maximum overclock. While frustrating, this is still a gas, as long as you maintain your enthusiasm. FWIW, NONE of my overclocked boxes have been unstable. The only casualties of overclocking have been motherboards dieing from volt mods and CPUs from stupidity.
P4s are an enigma. Take a look at Intel’s Thermal Management docs. You will note the temp sensor the motherboard reads is in the coolest part of the CPU, while the one that controls CPU throttling is in the hottest part of the CPU. I seriously doubt that the majority of aircooled P4 overclockers understand this but with P4s, cooling is king if you are going to overclock. Running at 9C over ambient at full load, my watercooled 1.8 GHz Prestonia Xeons do more work than a pair of 2.4 GHz Xeons running with stock heatsinks at 30C over ambient. Why? Clock throttling occurs at temperatures lower than what Intel would like you to believe. This may be contrary to what you have read on the (hardware?) Sites on the Net, but read Intel’s documentation on this and come to your own intelligent conclusion…
Reality? Unless you are a gamer, or practicing a slight overclock, you would be better served by purchasing a faster CPU or building a dually if you really use your computer.