One of the little known facts about MSE is that it can be used as an antivirus solution on Windows 2008 R2 Server. I use Windows 2008 R2 Datacenter as my workstation OS and I have been looking around for a good antivirus solution to be used with my OS and tried out many of the free antivirus softwares and none of them would even get installed on the Server machine, but as it turns out MSE works just fine on WIN2008 R2. it is free and doesn’t hog too much resources also.
You can get it from here http://www.microsoft.com/security/pc-security/mse.aspx