After opening up their first closed beta download just last week the Microsoft Security Essentials (MSE) Team has now made the beta download available to everyone.

If you want to try out the beta, which is extremely stable, then just head to the main MSE page and look for this download box:


Clicking that download link will take you to Microsoft’s Connect website, which requires a Windows Live ID account, and give you direct access to download the public beta.  This beta update will upgrade your currently installed version of MSE without the need to uninstall it first.

Just in case you need to know – the system requirements for the beta of MSE 4.0 are:

Operating System: Windows XP Service Pack 3 (SP3)*; Windows Vista (Service Pack 1, or Service Pack 2)*; Windows 7 (Service Pack 1)*

  • For Windows XP, a PC with a CPU clock speed of 500 MHz or higher, and 256 MB RAM or higher.

  • For Windows Vista and Windows 7, a PC with a CPU clock speed of 1.0 GHz or higher, and 1 GB RAM or higher.

  • VGA display of 800 × 600 or higher.

  • 200 MB of available hard disk space.

  • An Internet connection is required for installation and to download the latest virus and spyware definitions for Microsoft Security Essentials Beta.

  • Internet Browser:

    • Windows Internet Explorer 6.0 or later.

    • Mozilla Firefox 2.0 or later.

  • Microsoft Security Essentials Beta also supports Windows XP Mode in Windows 7. For more information see the system requirements for Windows XP Mode in Windows 7.

  • *Your PC must run genuine Windows to install Microsoft Security Essentials Beta. Learn more about genuine Windows.

If you discover any bugs or issues with the beta software be sure you take the time to report them in the MSE Answers Forums at

Congratulations – you’re a beta tester!