I've used numerous freeware AV programs through the years. Some were good, some were a royal pain in the a** and others were flat out terrible. AVG assigned all the .bin files in my system to itself. Didn't like that, ripped it out. Panda made a mess out of my system and even after uninstalling, cleaning the registry it STILL showed up in Services. Then I heard about Avast. Thought I'd give it a spin. That's been a long time ago and I'm still happy with it. I've recommended it to friends, all that switched are still using it. All are happy with it.
The 'voice'. My mom was visiting me and all of a sudden out pops the 'voice', "Virus database has been updated". Freaked her out, thought she was going to jump off the couch.