It will shut down XP if you do not Activate Windows XP.
Registering by using a name or address is optional but you must activate the system within 30 days.
Activation is required in 30 days from the first day that you start Windows XP. If you want to activate Windows on a day that is later than the day that you install it, a Windows Activation icon appears in the notification area. This icon periodically displays notifications to remind you about how much time remains before you must activate. After the 30 days has expired, you must activate Windows to continue using Windows.
During activation, you can also register your copy of Windows. Product activation is different from product registration because activation is required and registration is optional. If you want to register Windows XP by providing your name, e-mail address, and other contact information, you can also choose to receive information about product updates and other special offers.http://support.microsoft.com/kb/307890/
Edited by Enthusiast, 19 September 2006 - 04:49 PM.