Microsoft Security Essentials is a free* download from Microsoft that is simple to install, easy to use, and always kept up to date so you can be assured your PC is protected by the latest technology. It’s easy to tell if your PC is secure — when you’re green, you’re good. It’s that simple.
More info: http://www.microsoft.com/Security_essentials/ [3]
Links:
[1] http://pulse.veltsos.com/category/it/software/software/os/microsoft
[2] http://pulse.veltsos.com/category/it/security
[3] http://www.microsoft.com/Security_essentials/