How to Change a Windows XP Volume Licensing Product Key
To change the Volume Licensing product key on a computer that is running Windows XP SP1 or a later version of Windows XP, please refer to the following Microsoft Knowledge Base article:
How to change the Volume Licensing product key on a computer that is running Windows XP Service Pack 1 and later versions of Windows XP
How to change the Volume Licensing product key on a computer that is running Windows XP Service Pack 1 and later versions of Windows XP