Perhaps Windows Defender has been changed, although I do know that when I installed MSE (just as in Win 7) it automatically disabled Windows Defender. Edit: This article explains a little more about Windows Defender. it does indeed appear that Windows Defender includes a much beefier and wider array of defenses. Perhaps MSE is no longer needed. MS is also working with other AV/AM developers to ensure their products work well with WIn 8. I will be uninstalling MSE. Thanks for the info Dave.