Microsoft has silently released the final version of their popular antivirus software – Microsoft Security Essentials 2 and it’s now available for download from MSE official website. This free antivirus software from Microsoft could not only be used by home users but also by small businesses as well.
Having used it for more than an year, I’ve never had to rely on any other paid antivirus software to cleanup my system or had to face a virus attack. 
Microsoft Security Essentials has become one of the top rated and popular antivirus not just because it’s free, but due to its higher detection rate and better performance compared to other paid AV’s. The first version of MSE was released back in Sep 2009, and the latest one is Microsoft Security Essentials v2(2.0.657.0 ).
Features Of Microsoft Security Essentials 2
New Protection Engine: Improved the antimalware engine and could now detect new threats without getting latest definition updates.
Network Inspection system: Provides protection against network based threats
Windows Firewall Integration: Integrates into windows firewall and enables to turn it on or off.