In the past, we've praised the effectiveness of Avira's full security suite. The company's free antivirus package shares the same signature engine, so we weren't surprised to see it, too, score a very creditable 97% in this month's malware-detection test.
It also detected the majority of websites that other scanners reported as actively malicious, in each case relying on positive exploit detection rather than a blacklist.
The front-end isn't perfect: some quite basic settings appear only in Expert Mode, and in places you have to hover over obscure icons to find out what actions you can perform. But overall, it's clean and simple to set up and use.
As a bonus, AntiVir Personal has a tiny impact on system resources, taking a brisk seven seconds to initialise and occupying a modest RAM footprint.
So why no recommendation? One black mark is the absence of a firewall, but then none of the free packages offers that. Unusually, it also doesn't scan email, so dangerous attachments won't be spotted until you directly access them. This isn't a huge threat to your own security, but it means you could forward malware to others without realising it.
But what really turns us off AntiVir Personal is the huge window that pops up every time the signature database is updated (once a day, by default), stealing focus from whatever you may be doing at the time and nagging you to upgrade to one of Avira's commercial products. We understand the motive, but we'd rather trust our safety to AVG than put up with this sort of constant hectoring.