Understanding product keys
Product keys are required for all versions of Windows XP, for all languages, and for both 32-bit and 64-bit versions. Product keys are 25-character alphanumeric strings that are formatted in groups of five characters, separated by dashes. You must enter the product key during Setup to complete the installation. (If you acquired your computer from an Original Equipment Manufacturer, the manufacturer may have preconfigured the product key for the Windows XP software that is preinstalled on the computer).
Windows XP requires you to keep your product keys always available for your use and in a secure place. You must use only the product key assigned to this installation of Windows XP if you ever need to reinstall the operating system. If you attempt to use a product key from another Microsoft product, a beta program, or a different version of Windows XP, your installation will fail.
Each product key can only be used to install the software on a certain number of unique computers. The actual number of computers depends on your End User License Agreement. If you have received more than one product key, it is essential that you keep track of which product key you use to install the Windows XP operating system on each computer.
Automating the product key entry during Windows Product Activation
If you perform an unattended Setup, you can automate entry of the product key. In the [UserData] section of your unattended answer file, include the value of your product key in the ProductKey entry. For more information, see the Microsoft Windows Preinstallation Reference, located in \Support\Tools\deploy.cab on the Windows CD.
Windows XP provides two methods to automate activation.
If you perform an unattended Setup, you can configure the installation to activate automatically during Windows Welcome or Mini-Setup. For more information on unattended Setup, please see the Microsoft Windows Preinstallation Reference, located in \Support\Tools\deploy.cab on the Windows CD.
You can also use script activation through the Windows Product Activation WMI (Windows Management Instrumentation), which provides a number of useful query and activation methods.