Microsoft does not fully support this as if you try to install it normally it gives the below error:

Your version of the Windows operating system is not supported by this program.

Error code 0x8004FF04

 

  1. Download a copy of MSE from Microsoft: http://windows.microsoft.com/en-us/windows/security-essentials-all-versions
  2. Right Click on the mseinstall.exe
  3. Click on Properties.
  4. Click on the Compatibility tab.
  5. Check Run this program in compatibility mode for Select From the drop down menu Windows 7.
  6. Open a Command Prompt as Administrator. Navigate to your Downloads folder or where the installer is located example: cd C:\temp
  7. mseinstall /disableoslimit and follow the installer prompts