Microsoft Security Essentials Vista  4.1.522 Vista
Microsoft Security Essentials provides real-time protection for your home PC that guards against viruses, spyware, and other malicious software.
Microsoft Security Essentials is a free app that is easy to install, with a simple user interface. The app is periodically kept up to date so you can be assured your PC is protected by the latest technology. The graphical interface informs you when your PC is secure; when you're green, you're good. It's that simple.
Microsoft Security Essentials runs quietly and efficiently in the background so that you are free to use your PC the way you want - without any interruptions or long computer wait times.