To check, view or verify the Windows XP current activation status, open Run command from Start Menu, and run the following command:
oobe/msoobe /a
A “Activate Windows” dialog window will open to let user know the activation status. If the Windows XP has been activated, the message is “Windows is already activated. Click OK to exit.”

Else, you will be asked to let’s activate Windows now, which means that the copy of Windows XP installation is not yet activated.
*** INFO FROM INTERNET ***