What is Microsoft Security Essentials?

Microsoft Security Essentials is a free antivirus program for your personal computer, and provides real-time protection against viruses, spyware and other malicious software.

The program runs in the background while you're using your PC and checks daily for any updates from the Internet. It performs scheduled scans of your computer for any malware, automatically blocking most threats. Basically, if your Microsoft Security Essentials icon is displayed as green in the notification area, at the far right of the taskbar, your computer is in good condition. If the program detects a problem or threat, it displays a message with the detected item, the alert level, and the recommended action, so you can decide how to proceed. You can also use Microsoft Security Essentials to perform a manual scan of a file, a folder, or your entire PC, at any time.


  • Your computer must run genuine Windows to install Microsoft Security Essentials. To determine whether your version of Windows is genuine, see What is genuine Windows 7?

  • Microsoft Security Essentials is designed for personal computer users. If your business needs security, go to Forefront Client Security Downloads on the Microsoft TechNet website.

System requirements

Microsoft Security Essentials requires the following:

  • Operating system: Windows XP (Service Pack 2 or Service Pack 3); Windows Vista (Gold, Service Pack 1, or Service Pack 2); Windows 7

    • 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.

  • A VGA monitor with 800 × 600 pixels or higher resolution.

  • 140 MB of available hard disk space.

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

  • Internet browser: Windows Internet Explorer 6.0 or later; Mozilla Firefox 2.0 or later

Microsoft Security Essentials also supports Windows XP Mode in Windows 7. For more information, see Install and use Windows XP Mode in Windows 7.

To install Microsoft Security Essentials

  1. Go to the Microsoft Security Essentials website, and click the Download Now button.

    Depending on your browser, you might be prompted to download a file or select the version of Windows you're using.

  2. Click Run.

    If you are prompted for confirmation, click Yes or Continue.

  3. In the Microsoft Security Essentials installation wizard, click Next.

  4. Review the Microsoft Security Essentials Licensing Agreement, and then click I accept.

  5. Click Validate to confirm that your copy of Windows is genuine.

  6. Click Install.

    The installation should take approximately three minutes.

  7. When the installation is complete, click Finish.

    Microsoft Security Essentials automatically checks for any online updates, scans your PC for potential problems, and alerts you to any problems by displaying a message in the notification area, at the far right of the taskbar.

For more information, go to the Microsoft Security Essentials website.