Microsoft Security Essentials which is the first antivirus software owned by Microsoft is compatible with the series of Microsoft operating systems, namely Windows XP, Windows Vista, and Windows 7.You can download free anti-virus for Microsoft Security Essentials Microsoft.While Microsoft Security Essentials only available for some countries like the United States, Israel, China, and Brazil. Free if you download the Microsoft Security Essentials for PC or netbook, you can do here through the Microsoft Security Essentials Microsoft site.Antivirus also automatically updated on a regular basis with a prescribed schedule, so do not be afraid when you use this antivirus, provided that connect the Internet, antivirus Microsoft Security Essentials will begin running the latest version.The MSE performance analysis comes from av-test.org, a group that routinely publishes the results of anti-virus stress tests. AV-Test ran MSE against 3,732 samples of malware that are currently infecting PCs around the world, and found that the program blocked all of them, both when the samples were opened or accessed and when the malware was manually scanned.