im thinking probably not. its uncommon for prebuilts to support overclocking and/or unlocking, there are only a few that do. i dont believe HP has ever been one to support such things though youre welcome to check your bios for said options.
short of that, a new motherboard would be required to unlock and/or overclock your processor..and thats based on the assumption that youre referring to a phenom II x3.
first gen phenom's arent unlockable period, and were hardly overclockable on even the best boards