How to change your Windows XP product key when you suspect piracy

Lately I came across a situation where I had to re-install Windows XP on machine from scratch using an OEM install CD, I had an OEM CD that installed on the machine without any problem, but it did an auto install with the key that came with it.

I wanted to change this key so I don't run into issues with software piracy and resulting woes with windows update, Microsoft Genuine Advantage failures etc. There might be other occasions when you buy a used computer from somebody with Windows pre-installed and want to change the key to a genuine legal Windows XP registration serial key. Here is how you change the Windows XP product key:

- Open regedit to edit the registry (Start -> run -> type "regedit" without quotes and hit enter)

- Navigate to HKEY_LOCAL_MACHINE\Software\Microsoft\WindowsNT\Current Version\WPAEvents key

- Right click on the OOBETimer and choose modify

- At least change one Hex value pair, such as change FF to 11 (doing this "deactivates" Windows)

- Click Start -> Run -> Type "%systemroot%\system32\oobe\msoobe.exe /a" without quotes and hit enter

- A Windows product activation prompt would appear, choose to "telephone a customer service rep at Microsoft to activate Windows"

- Click next

- Click change product key - change your product key here and restart your machine

Please note that there is a different procedure to be changing a "leaked volume licensing" key (typically used in large corporations). The instructions from Microsoft on how to do this are at: