Well, according to Dell's site, it's a P4, possibly with HT. What do you plan on doing with it?
EDIT: It is 775 because of the 945G. But the question remains, what do you plan on doing with it? I wouldn't spend a whole lot on a LGA775 board, it's a dead end socket. Do you need PCIe? Do you need onboard video? All things we need to know