On my Pro 1, which I have had since the day it was released (Feb 2013) I depend on the built in Microsoft Security Essentials and the Defender. This is my main computer which I use for several hours every day all over the internet. I have never had a virus, (knock wood to appease the spirits of the forest) so far. Malware, which changes my home page or my search engine, is easily removed when it rears its ugly head. I have two more laptops that I use on occasion, and my several friend's computers. None of these devices have ever had a serious malware infestation if they were running Microsoft Security Essentials or Windows 8, which has it built in to the os.