Here is the setupp.ini file:
[Pid]
ExtraData=786F687170637175716954806365EF
Pid=76487OEM
That's it. Look at the Pid line. It does not matter what the first 5 numbers are, but if you change the OEM to 335 (these need to be exact), you can make a retail version, for which only retail keys will work. Retail is what you would have purchased if you walked into Fry's or Best Buy. The OEM version came when you purchased a "custom" built computer. If you change the last three digits to "270", you'd have a corporate, volume licensed version of XP. You could also make an upgrade version as well.
I don't think you will have much luck slipstreaming an HP version. Versions of Widows licensed to Dell, HP, Compaq, etc., are a little different and at least with a Dell version, you will get an error when you try to SS a new SP.
It's not difficult to create an HP XP CD, format and install on one computer, then you can issue a command to "shrink wrap" the install, then ghost it to as many drives as you want. Doing this, it'll be like when you purchase a new computer and you get the "Lets spend a few minutes together". You'd still have to install the latest SP, but if they are all connected to a server, get the standalone version of the SP, put it on the server and point all the wkstations to the file.
Using this program, you can read the keys off of any Win2000/XP machine. It'll even tell you the key for Office...
http://magicaljellybean.com/keyfinder/
It is a great utility if the sticker is no longer (or never was) on the computer. There are even tools for changing the key..
Thanks for the compliment. I've been around computers a long time. I've even tried to get out of the industry, but kept coming back.