In my opinion the reason for that is the bad Publicity that Microsoft has since Windows is on the Market becasuse it has so many wholes and security problems. I would also say that people are feed up with Microsoft because due to that. They even can't fix security wholes which have been long open and which Security Expert seay it is dangerous to leave it open. Because of that people are changing their OS to something which is better e.g. Linux. For that reason Microsoft wants to buy NAI to send a signal to buyers of their Windows OS that their OS will be secure and stable. But will it work? I don't think so. In order to make Windows OS better they should reprogramme the whole OS.