I dunno what socket number your systems uses...P4 uses a variety of skt numbers, right? Download CPUz and it'll tell you your skt number. The socket connects the CPU to the mobo... the pin arrangement varies
It's probably a socket 478. If that's the case, get the ASUS P4P800SE motherboard. Newegg has it for $94 and it's an excellent board, that gives you many options.