Currently I'm using Avira AntiVir (the free version). Generally it's okay but there's two annoyances.
It updates when it feels like doing so on a daily basis, and it also likes to give you an ad while updating. And the virus definition servers are like, located in the moon and is relatively hard to connect to.
That happens usually when I'm playing TF2, and then whoalagspike. Thankfully, it doesn't automatically alt-tab me, but it's still quite annoying.
Is there a less annoying antivirus out there (and free, and good enough)?