happens to be once a week with NAV 2004 and once every 2 or 3 weeks with Housecall. I have NAV set to automatically scan the same time every week.
I have always generally relied on my AV software to alert me when an infection appears. I have not, in the past, scanned my hard drive often-- maybe once per month if that.
Perhaps I've been fortunate because I've never had a bad infection. I always keep my AV up to date and have been using a firewall for years etc. (I do scan religiously for spyware-- weekly-- as I find that more worrisome than any virus-- because I've been assuming that my AVG will "flag" anything right away).
This has worked for me-- but I am wondering if I should scan more frequently and also wonder if perhaps I should do additional scans beyond my "usual" onboard AVG free. (On the rare occasions where I think I may be infected I do go to Trend Micro and allow that to scan, and also download Avast! and allows that a scan as well.) But, that is only when I think there is something amiss (for example, when I 1st noticed that emails from a sober were being returned to my address, I assumed my pc was infected-- not so, as that particular virus was a spoof virus).
How often and what "additional" products do others use for virus scans?