I quit using avast when it kept letting viruses through my mom's computer and AVG has turned into a piece of shit, slow, full of false positives did I say slow.

Essentials has been wonderful, it even catches all my software cracks and flags them. Lol. It has caught multiple Java exploits and blocked them too, those are times when you scroll across an advertisement and then it tries to download malware or redirect you to a different site.

My only complaint is that even though I have it set for an automatic weekly scan it sometimes doesn't seem to do the scan and tells me my computer might be vulnerable until I manually do the scan. Honestly, I haven't pursued figuring out why, it might be in my settings and not their issue at all.

I would recommend MS Security Essentials to anybody.