I'm something of an old-timer, was taught in the old days to
never scan a computer from a program on the same computer. After first acquiring internet access, about 6 or 7 years ago, I still did scans from "outside", places like HouseCall.
I first got referred to avast a couple of years ago by friends at one of my online medical support groups -- they commented that on a number of occasions avast had caught things for them that had slipped past Norton.
And of course discovering the great support forums here, and learning what a nightmare NAV can be, only came afterwards, and were icing on the cake, so to speak.