Heres the guide to what this whole thread is on about:-

http://support.microsoft.com/kb/155197

Its all put in manually by the the user, I do not like Microsoft that much, but they are not stupid enough to have the product key in a text file.

I used to release the CZFXP versions of Windows XP but always used the normal setup rather than unattended, therefore no unattended setup information was saved. And to be honest on any file sharing forum theres probably little chance of a "Genuine" XP download.