If the CPU is unlocked and the bios supports over clocking, I'd try the Northwood first.
Baby steps now. P4's are easy to smoke.
You shouldn't let a P4 get over 120F. The built in temp shut down is 140F.
I am gonna do some more research, What do you think a good stable speed would be?
I'm probably one of the least experienced overclockers around here but I think this would be difficult to tell for even an experienced OC'er.
I've seen these P4s being pushed to 5.4Ghz before but that was extreme.
Personally being an amateur overclocker, i'd be happy getting to 3.2 / 3.4 kind of area.
But a lot depends on the options in your mobo bios
Those old P4s overclock like $h1t. If i'm not mistaken, the only thing you can change is the FSB.