To change your Windows XP product key, you'll need to use the Windows Product Key Update Tool. Before running the tool, read all instructions to make sure that you understand how the tool works and what information is sent to Microsoft as part of the update process.
How it works
The Windows Product Key Update Tool will make changes to your Windows installation to update your product key. In addition, the tool will scan a number of key Windows files to determine if they have been tampered with. If tampered files are discovered, the Windows Product Key Update Tool will alert you before continuing.
What information is collected
Using the Windows Product Key Update Tool results in information being sent to Microsoft. The information collected will not be used to identify or contact you. The information sent is standard Windows validation information as well as information related to the file tampering scan.
Note: Microsoft recommends creating a system restore point before making any operating system changes.
You'll need your 25-digit product key to complete the product key update process. For examples of where to find your product key, visit the How To Tell website.
To update your product key
Open the Windows Product Key Update Tool.
When prompted to run or save the Windows Product Key Update Tool installer, click Run.
Follow the instructions in the installer.
After updating your product key, you will be required to activate Windows XP. If you still have issues after running the tool or with activation, visit the Windows XP Solution Center on the Microsoft Support website for additional assistance.