Which P4 chip is best for overclocking?

Between the Northwood 3.0, 3.2, 3.4 and Prescott 3.0, 3.2, 3.4?
Rig is going to be watercooled. I am leaning towards a 3.2 northwood, but am unsure if the steppings on the others would enable easier overclocking? Ive just read that i might be better off with a 3.0?!?

From what I've been reading the 3.0C is the best overclocker right now.

Cool, yeah thats what i just read after doing a little more digging. I guess i am going to need really high end ram for that though.
Has anyone tried the 3.4C yet? Its a bit pricey though!

Depends on what you mean by "best overclocker"? Do you mean best bang for the buck, or best percentage overclock, or just plain highest CPU clock speed? The 3.4C might give you the top speed, but at almost half the price, the 3.0C is the best bargain. Also, if overclocked to the same CPU clock speed, the 3.0C with it's higher FSB and higher DDR speed will out perform the 3.4C.

Plain highest (performance overall) - without going mad on price. So if for double the price i get a couple of mhz more it aint worth it.

So 3.0C is looking the product of choice. Doing a bit of reading, whats this "30 cap" stuff all about? Does this mean only certain 3.0c's are any good, and there are other 3.0Cs that arent? How can i tell which is which?

Oh, and assuming no memory restrictions, what sort of clock am i likely to get with watercooling? Board is likely to be a Gigabyte GA-8KNXP.

I think he means highest CPU speed.