Avira Antivir Personal

Avira AntiVir Personal's excellent malware detection, disinfection, and scan speed earned it the top spot in our ranking of free antivirus software. Its interface could be better, though, and using the app means putting up with daily pop-up ads.

In AV-Test.org tests, AntiVir's 98.9 percent overall malware detection rate was unbeaten. AntiVir was also tops in proactive-protection tests that use two- and four-week-old signature databases to simulate the detection of new, unknown malware, with rates of 52.7 percent and 45.5 percent, respectively.

The strong performance continued in disinfection tests. Avira Antivir Personal found and disarmed all of the rootkits and other malware infections tossed at it, though (like all the free antivirus software we tested) it tended to leave some remnants, such as relatively harmless Registry changes, in place.

Avira Antivir Personal was not just the most thorough free tool we tested, but also the fastest. It led in speed tests for both on-demand scans (which you schedule or start manually) and on-access scans (which happen automatically during tasks such as copying files).

If Avira Antivir Personal's interface were as polished as its malware-fighting ability, it would be a no-brainer recommendation. But its daily pop-up ads for Avira's paid ID-theft protection software could easily annoy many users, and at times its interface feels better suited to advanced users.

For example, Avira Antivir Personal's installer prompts you to select among ‘extended threat categories'. Some are obvious, such as games or jokes, but you might be forgiven for not knowing whether to pick ‘unusual runtime compression' (listed in Avira's online help as ‘Files that have been compressed using an unusual tool and are therefore suspicious').

In a similar vein, Avira Antivir Personal's detection pop-ups offer too many choices and don't suggest the option most appropriate for the average user. It checks the ‘Deny access' option by default, but that choice would leave the discovered malware sitting on your PC; you would continue to receive warnings until you opted to delete or quarantine the discovery (you can also choose to rename or ignore the file).