MS says:
"You cannot use Add or Remove Programs to remove the notifications. You can
temporarily disable Windows Genuine Advantage Notification Prompts. To do
this, right-click the Notifier icon in the notification area and select
Change Notification Settings. Then, follow the prompts. This will disable the
Notification Prompts until a new release of the Notification Update is
released."
If you can see a notification icon on your desktop, it is an indication that
your copy of Windows XP may not be genuine. I do not see such an icon,
because my copy is genuine.
Alternatively, you may have a download of an update KB905747, but I cannot
see such an update myself.