How to use OEM Version to Upgrade Windows XP

[electricsketchbook]

Hi,

I've got here a PC with a proper windows product key, but in my haste I've installed using the incorrect flavour of windows. I used the retail flavour instead of OEM. I forgot which version of xp I owned so I chose one of them and installed it. My legit cd key didn't work so I just ended up using another one I got off the net. How to use OEM Version to Upgrade Windows XP? Can it be installed on more than one computer? Whats the real difference between OEM and retail version?

[Mac-Imagery]

There's no difference between a fully installable OEM version and the standard retail version of XP. There is a major difference between the licences though. To use OEM Version to Upgrade Windows XP, you need to use a OEM version of the Windows XP install CD when using the key you find on the bottom of the laptop.

[SimonBoss]

WinXP's setupp.ini controls how the CD acts. IE is it an OEM version or retail? First, find your setupp.ini file in the i386 directory on your WinXP CD. Open it up, it'll look something like this:

ExtraData=707A667567736F696F697911AE7E05
Pid=55034000

The Pid value is what we're interested in. What's there now looks like a standard default. There are special numbers that determine if it's a retail, oem, or volume license edition. First, we break down that number into two parts. The first five digits determines how the CD will behave, ie 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 determines what CD key it will accept. You are able to mix and match these values. For example you could make a WinXP cd that acted like a retail cd, yet accepted OEM keys. Now, for the actual values. Remember the first and last values are interchangable, but usually you'd keep them as a pair:

Retail = 51882 335
Volume License = 51883 270
OEM = 82503 OEM
So if you wanted a retail CD that took retail keys, the last line of your setupp.ini file would read:
Pid=51882335
And if you wanted a retail CD that took OEM keys, you'd use:
Pid=51882OEM

[Dammit]

If you want to format and reinstall you will need to start (boot) your computer with windows XP disk in cdrom. 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. Note that when you change the PID, you aren't changing the version of Windows on the disc - only the types of license keys it will accept. It is not technically the same thing.