This trick will show you how to change Windows XP
product key without re-installing the operating system. This makes it possible
to install a new genuine key without the need to format and re-install your
Windows XP.
1. Goto start menu, run, type regedit
2. In registry editor goto
HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\WINDOWS
NT\CURRENT VERSION\WPA EVENTS
3. In the right panel open OOBE Timer
4. Edit/Change atleast one entry there, press OK and
close registry editor.
5. In run type the following command
%systemroot%\system32\oobe\msoobe
/a
and press enter
6. Activation wizard appears
7. Select activation by phone and in the next screen
select the option CHANGE PRODUCT KEY, enter a valid corporate product key,
press OK and close the wizard
8. Reboot the computer and type the same command in
the Run
9. Activation wizard appears again and it shows the
message WINDOWS IS ALREADY ACTIVATED
CHANGING WINDOWS XP PRODUCT KEY WITHOUT RE-INSTALLATION