Is there some specific meaning to "unlock BIOS"? Unlock multiplier? What CPU do you have in that PC? Does it have an unlocked multiplier? I doubt that it has the Intel "Z" series chipset that is generally required for overclocking on Intel.
In short, I don't think (offhand, at least), that you're going to be able to do what you think that you might be able to do with this.
I would love to stand corrected, and see someone overclock a locked CPU in an OEM branded PC, but generally, that doesn't really happen.
Need to buy an Alienware or Falcon Northwest or something next time.