Changing XP Pro CD Key
If you just recently purchased XP Corp edition and dont want to do a new install to change your serial number.
As with any registry edit ..Please back up your registry before doing the following.
Change Product Key without Reinstall:
1. Run regedit and go to: HKey_Local_Machine\Software\Microsoft\WindowsNT\Current Version\WPAEvents, on the right double click on "oobetimer" and change at least one digit of this value to deactivate wind0ws.
2. Choose run from start menu and type in this command:
%systemroot%\system32\oobe\msoobe.exe /a to get the activation screen and go to the second option which is activate by phone.
3. In the new screen choose the option to change product key, and type in the new product key (Corporate one only).
4. Close that window, reboot your system and enter the command in step 2 for the second time to verify your activation , you should see "windows is already activated".
all there is to it.