Microsofts new anti-piracy ploy, which makes you verify that you have a legal copy of windows before getting add-ons or non-essential updates from MS Update.
http://money.cnn.com/2005/01/26/technology/microsoft_piracy.reut/index.htm?cnn=yes
http://money.cnn.com/2005/01/26/technology/microsoft_piracy.reut/index.htm?cnn=yes