Back in June 2009, Microsoft had released the beta version of the new antivirus software for Windows named Microsoft Security Essentials. Microsoft Security Essentials which did well in most of the tests is now out of beta and the final version is released today and available for download. This antivirus software is completely free of cost from Microsoft. You can start download MSE for Windows XP, Vista and Windows 7 from the MSE Website.
The download file size is just over 4 MB in size and the installation is very simple and easy. Microsoft Security Essentials provides real-time protection for your home PC that guards against viruses, spyware, and other malicious software. You will need to validate copy of Windows before installing MSE.
If you were a beta tester, you can upgrade to latest version of Microsoft Security Essentials.