They call it WGA = windows genuine advantage remover. Lumalabas yan once your system has been detected na pirated version xa. When you register a pirated Win XP, lalabas yan tlga. Good thing there is a WGA remover.
There is a utility that removes this pesky notification. Just download and run it. http://www.softpedia.com/get/Tweak/Uninstallers/RemoveWGA.shtml