Microsoft has released a new version of Microsoft Security Essentials, the free anti-virus/anti-malware program for Windows PCs. The MSE 4.0 release is available via the Microsoft Download Center and the MSE Web site and also made available to existing customers automatically through the Microsoft Update service.
Interestingly, this version has been in beta since late 2011, and the last released version was 2.1. There is no indication of the need to skip v3 and the jump to v4; the latest build being 4.0.1526.0. The participants in the beta program who are subscribed to automatic updates will be upgraded to the final release of the latest version of Microsoft Security Essentials after they agree to a new license agreement. You can also do a manual upgrade from v2.1 or the beta release without uninstalling the previously installed version.
Microsoft Security Essentials provides real-time protection for your home or small business PCs (up to 10) that guards against viruses, spyware, and other malicious software. MSE is designed to be simple to install and easy to use. It runs quietly in the background without annoying notifications or interruptions. It is available as a free download from Microsoft for genuine Windows users, in both x86 and x64 editions.