While you may not see any ill affects of running both at the same time, it's typically not a good idea. You could disable the active scanning of MSE and use it for just passive scanning.
It is always a bad idea to run them both at the same time. They will interfere with each other, slowing down your system and will not provide the protection that just one provides.
A forum community dedicated to tech experts and enthusiasts. Come join the discussion about articles, computer security, Mac, Microsoft, Linux, hardware, networking, gaming, reviews, accessories, and more!