I think what is really telling, whether the AV software is free or not, is the number of false positives or misses that it reports.
Being in IT, we kinda live on the edge here at the office (I'll go no further than that
) and we have submitted files to
www.virustotal.com, which will scan files with about 40 AV products and shows which report issues and which don't.
Needless to say, it's a crapshoot. No single tool will catch it all. Period.
And I always wonder, with the number of AV programs that come out of Eastern Europe, how many of these are really trustworthy? I know for the longest time Kaspersky was considered to be all but a virus author...
As always, if you're careful what sites you visit, are cognizant of phishing attempts and don't open suspicious attachments (turning off "hide file extensions" is a good place to start), you'll be good to go whether you use IE, FF, Opera or even lynx at a CMD prompt.
Myself, I get by with a paid subscription to AVG AV
only at home, Micro$oft's Windows Defender, ClamAV (free open source) for my Linux server and ad-hoc scanning on Windows, and the company's corporate Trend Micro software on the laptop.