You can check out comparisons of anti-virus products here: <a class="postlink" href="http://www.av-comparatives.org" onclick="window.open(this.href);return false;">http://www.av-comparatives.org</a> They publish reports on many different things, some of it you might find hard to interpret. They produce annual summary reports which are easier to understand but as they do them in December, the current one is nearly a year out of date, which is a long time in the world of the anti-virus. Here is 2012's: <a class="postlink" href="http://www.av-comparatives.org/wp-content/uploads/2013/01/avc_sum_201212_en.pdf" onclick="window.open(this.href);return false;">http://www.av-comparatives.org/wp-conte ... 212_en.pdf</a>
Their top-rated products for 2012 were:
- Avast
- AVIRA
- Bitdefender
- Bullguard
- ESET
- F-Secure
- G DATA
- Kaspersky
You can see a chart of real-world blocking of threats here which is updated monthly: <a class="postlink" href="http://chart.av-comparatives.org/chart1.php" onclick="window.open(this.href);return false;">http://chart.av-comparatives.org/chart1.php</a> There's no need to consider anything that has less than 99% effectiveness as far as I'm concerned because both
Avast and
Avira have free versions.
Personally I use Avira because it is feather light (the best of all anti viruses) for taking up system resources (i.e. apart from when doing a full scan will not slow your computer down at all). Avast is also excellent in this respect, and is only marginally behind it. I continue to stand by Avira because it has served me very well for years and is very very consistent. Some of these anti viruses experience big swings in effectiveness, some of the ones which used to be bad are now good and vice versa, Avira has always been one of the best for protection. However, I cannot pretend it's perfect, I think Avast is more user friendly. With it being very popular though it may suffer from the 'tallest nail' effect where it is purposefully targeted and therefore whilst very little gets through, what does get through will be more likely to effect Avast than Avira. Sometimes there is such a thing as 'security through obscurity'. That's probably just me being paranoid though. So, if you're thinking free only, those two are your best bets and I see no reason not to use one of those two and pay for one of the other ones.
An anti-virus is not enough though. An anti-virus is like having a burglar alarm and a weapon in the house to twat a burglar with, and having an effective weapon does count, you don't want to be hitting the fucker with a pillow when you needn't. However, the best thing is to stop them getting in in the first place. For that, make you sure you sure you've got a decent firewall. I use Comodo but I'm a geek and security paranoid. Even I find it a little bit annoying. Most people would lose their rag with the amount of alerts it gives you. For that reason, I do not recommend it to people who already find computers annoying because it will drive you around the fucking bend.
ZoneAlarm, like Avast, is also excellent and more user friendly.
You may want to consider a HIPS. I won't go into what it stands for, I'll just tell you what it does. If a firewall is locks for your doors, an anti-virus is a combination of burglar alarm and a weapon to twat him with, a HIPS is the last defence if the burglar has found your keys or picked the lock, deactivated the burglar alarm so you're still asleep with your weapon upstairs or else has tied you up, the HIPS is like having all your most valuable possessions glued down so the clever burglar can't take them. What it does is monitor key files and settings for changes so that anything that gets in finds it really difficult to change anything important. Most people don't bother with one and that's fair enough, they can be a bit annoying because they give off alerts when you install new software because it is you changing those key files and settings. However, with all the trailware you get these days, you know, the shit that frustratingly adds new toolbars to your browser and a new fucking home page and changes your search engine, they can be useful against other annoyances as well. There's a lot less choice here but they're all free:
Malware Defender,
WinPatrol,
MJ Registry Watcher.
Finally, there are the dedicated malware removers when the worst has happened and something has got through and infected your system.
Malwarebytes is the best and it's free.
Have inserted download links for all products mentioned.