Prerelease version 4.4 for Microsoft Security Essentials has been released. Microsoft has recently in July this year, released 4.3 version for Security Essentials, now is testing 4.4 prerelease version and is available to download for testing and feedback purposes. Microsoft Security Essentials 4.4 207.0 Prerelease version can be installed on Windows XP, Windows Vista, and on Windows 7 but not Windows 8 as it is not compatible.
Before installing this version, make sure to uninstall already installed MSE from your computer [Fix It for MSE is also available, if you can’t remove it]. If you install this MSE prerelease version, its updates will be automatically installed through Microsoft Updates. And you’ll be enrolled in Microsoft Error Reporting, Customer Experience Improvement program and Microsoft Active Protection service.
Download Microsoft Security Essentials 126.96.36.199 prerelease from here.