Changing the product key that you used to install Windows with might be necessary if you find out that your current product key is illegal. You could completely reinstall Windows using your valid key code but changing the product key is considerably easier.
The steps involved in changing your product key differ considerably depending on which Windows operating system you're using:
- How To Change the Windows 7 Product Key
- How To Change the Windows Vista Product Key
- How To Change the Windows XP Product Key
Important: Please be aware that you'll be required to reactivate Windows after changing the product key.