The initial code is part of the bios programming apparently. Once you press the right key or keys that starts up a predisposed program instructing the reformat and reinstallation of Windows and the prepackages softwares a system comes with.
Someone with a used laptop now wants their own copy of XP installed there to replace the original so they can see a fresh registration. The problem with a laptop is where are the drivers? On some you won't find the normal support pages for updates like you would for a desktop or boards in a custom case.