The reason I decided to go with MSE was that it was the most lightweight antivirus out there. It never annoys me unless it sees something nasty go by. It doesn't put a strain on my system. It doesn't bother me constantly about renewing anything. It doesn't prevent me from going to any websites or from setting up a networkable printer (which I've seen several times with stupid Norton). MSE gets out of my way and gives me some security.