You ask 20 people which anti-virus program they like and there's a chance you may get 20 different answers. Each anti-virus product practically claims at one time or another they have a better and higher detection rates than each other, and each often submits themselves to some virus detection board, magazine, or website, to see whose better this month or quarter than the next guy. Over the past 10 yrs I've used at one point or another: Norton/Symantec, McAfee, Bitdefender, Kaspersky, AVG, Avast, Avira/Anvir, Dr Web, Panda, Trend Micro, CA.
There's probably 10 or so more common and recognizable names out of about 30 or more choices, see: [ame]http://en.wikipedia.org/wiki/List_of_antivirus_software[/ame] and
http://virscan.org/
I've often seen over the past 10 yrs or more that one antivirus product might be the shining star and flavor-of-the-month by one testing board, magazine, website, etc, this month but not the next. And there's so many different boards, websites, and magazines that test these products, and often they will disagree on which product is best, thus making it hard to find one product that's consistentlY 90% OR more of the time considered "the one that all of them always love no matter what". It all becomes confusing as hell.
Lots of them go around implying "we catch every virus, or heuristic, or unknown virus, or compressed file virus, or .exe virus, emailed virus, etc...better than XYZ company does.
When it gets down to it, IMO, it's all a matter of personal preference, just jumping in and picking one.
Bottomline...I've yet to find a antivirus product that catches EVERYTHING on my PC. Never have any of the following done so for me when they claimed too...Symantec/Norton, McAfee, AVG, Avast, Anvir/Avira, Kaspersky, Bitdefender, Panda, Trend, Dr. Web. How am I able to say that?
I download a lot of "stuff" online on one of my PC's that's dedicated strictly to doing that. It ends-up catching more viruses than probably the casual or average users PC. Sometimes I'll run multiple free online website scans by each major antivirus company, along with whatever anti-virus software is installed. Whichever anti-virus I have installed this month will sometimes miss a virus, yet another companies free online scan will sometimes catch it. Because of that, and uninstalling and reinstalling antivirus products and seeing different things caught, I don't believe any of them are truly 100% at catching every virus. I believe most of them catch maybe 95-99.xxxxx% of them. Sometimes it could be a false-positive when one company claims to find something on my PC and another one can't, who knows, but why take a chance on it if one does, and waste time trying to figure it out. OTOH, if you aren't downloading lots of "stuff", then you probably won't have as many virus problems, compared to those of us who do.
Something else to keep in mind...many people feel that certain anti-virus products are doing so much work in the background that they are slowing down your PC (maybe Symantec/Norton, McAfee, some claim that of the AVG suites, and those opinions will vary). There's some truth to that but it often depends on your PC, memory, processor, other tasks and resources going on the background.
Personally, I'd try a couple of the free ones out for a few days, and see which one you like best. Maybe either an Avast, AVG, Anvira/Anvir...notice how they all start with "A's", lol. Right now I like Avast, but that could change if I start to notice it not catching lots of stuff, and that always seems to happen at some point with whichever one I'm trying now.
Best thing I believe someone can do is just dive-in, pick one, see if it slows-down your computer so much you can't stand it, and if you don't like it in a few days, uninstall it and try another one.
Also, I would encourage searching on Google for the major free online scans by the different virus companies, and periodically running their free online scans, just to make sure you don't have something on your PC that whatever product you picked, wasn't able to catch.