I've tried many antivirus options on my PCs. Yesterday I uninstalled Microsoft Security Essentials yet again knowing it isn't really up to scratch (I had it for convenience sake after an O/S reinstall) and having tried most of the common free and paid for A/V brands, I downloaded the less well known Baidu Antivirus 2015. What a nice set of software this is, very accomplished. It uses it's own A/V engine and gives you the option of running the rather good Avira engine as well. Very nice and twice the safety. There are a number of handy facilities included, a sandbox, a plugin remover, language translator, private browsing, its own firewall (surprising how many free A/V suites don't have one), ad blocking to speed page loading, an anti homepage hijack facility (my brother could have done with this, it's just happened to him), secure file deletion, and a 'one click' system repair tool to speed things up. This is a free application by the way.
If this turns out to be as good as the Baidu browser, it'll be a class act. Their browser is the best I've tried, very attractive, fast and no flaws.