The Pid value is what we're in this for. What's there now looks like a standard default, but that is no good. There are special numbers that determine if it's a retail, OEM, or volume license edition. First, we must break down that number into two parts. The first five digits determines how the CD will behave, i.e. is it a retail CD that lets you clean install or upgrade, or an OEM CD that only lets you perform a clean install? The last three digits determine what CD key it will accept.
You are able to mix and match these values. For example you could make a Windows XP CD that acted like a retail CD, but then yet accepted OEM keys.
This is in my opinion a very useful tweak if done properly, so listen up!
Here are the individual values, the first and last values are interchangeable but you should keep them together:
Now if you wanted a retail CD that accepted the retail CD key then you would use.
Pid=51882335
And if you wanted a retail CD that accepted OEM keys, you'd use:
Pid=51882OEM
Warning!
I've had some reader feedbacks suggesting the fact that after performing the steps described on this page they were in fact successful in installing XP, however they were no longer able to activate their machine. Some even went around and just formatted their hard disk.
Make your CD
After messing with the files as described in the tip you'll need to re-create your CD and make it bootable, so you'll be able to install Windows from it.
The best tool that I know of to help you create a bootable Windows CD is Bart's BootCD. It's well worth the effort and it's free:
Bart's way to create bootable CD-Roms (for Windows/Dos)
Tips and Tricks 
