Because of changes in Windows XP Service Pack 1 (SP1), Windows XP-based computers that use a leaked product key that is known to be available to the general public may not be able to install SP1 or automatically obtain updates from the Windows Update Web site. For an easy and quick method of obtaining your own CD Key please read Quickly Retrieve Windows CD Key.
For example, you may experience the symptoms that are described in the following Microsoft Knowledge Base article when you install SP1 - The Product Key Used to Install Windows Is Invalid
There are two (legal) methods that you can use to change the product key with volume licensing media after installation. You can use either the Windows Activation Wizard graphical user interface (GUI) or a Windows Management Instrumentation (WMI) script.
