In favor of another free one : AVG.
Avast may well function fine, but the nag screens of the versions I tried were too much for me when I tried it.
I will admit that I have a very low tolerance level to nag screens (basically I see one and you're toast).
AVG works fine and doesn't nag. I am building an intolerance to the update process though - the way the app pushes its popup to the front and over anything else I may be doing is starting to get on my nerves.

Ill be happy to use avast as long as they never feel the need to bloat out their software like so many of the largest AV providers. It seems that as soon as Norton AV set the standard in useless, obtrusive, resource hunry software, the rest of the industy leaders followed suit, providing "Internet Security" bundles, that had a preformance hit so great, they were worse than most viruses.

If avast goes down that road, ill be suprised and dissapointed. Lets pray they keep to a lean mean fighting machine.

Having just unpicked a malware attack by WinAble and the misleadlingly named AVSystemCare I'm not so sure about Avast. Avast certainly did scream like a girlie (which was a good thing) but most of the disentangling was courtesy of the Bleeping Computer site and my knowledge of DOS and the Registry. Of the software solutions I found SuperAntiSpyWare most useful. But I like Avast because it's free and unobtrusive.

I've been using Avast! for three years and have yet to see a nag screen, I define nag screens as pop ups. It has worked well for me and you can disable any module from the task bar.

But no nags, maybe Mr. Monett did not register the software and was getting register nags to be fair, but there are no nags for the registered software and I thought I would correct the notion that Avast! is nagware, it is not.