I found NON of the boughten ones work as well as these:They are all FREE !!!!Computer MaintenanceAdvanced WindowsCare V2 Personalhttp://www.iobit.com/advancedwindowscare...CCleanerhttp://www.ccleaner.com/Spybot S&D>>...>.......http://www.safer-networking.org/en/>.......Ad Aware 2008http://www.download.com/ad-aware-2008/30...Avira AntiVir® PersonalEdition Classic....http://www.free-av.com/I've been using them all for over two years now.They are all compatible with each other and Windows XP and Vista as well as older versions of Windows and Linux.You will have a trouble free, clean, green, mean machine.