Microsoft Security Essentials was the only entry to fail AV-Test's certification between September and October – an embarrasing slip for the once well-regarded virus protection solution. MSSE received a total of 10.5 out of 18 possible points, most notably falling short in zero-day malware attacks. As a point of reference, 11 points are required to receive certification. The fallen AV only received 1.5 out of 6.0 for system protection, but fared better when it came to repairing infections and usability: 3.5 and 5.5 out of 6.0, respectively.

Thankfully, other free alternatives performed better: Avast (14 points) edged out AVG (12.5 points) and Avira (12 points), receiving above-average marks all-around. Meanwhile, Bitdefender topped payware offerings, netting an almost perfect score of 17 points.

If you're somehow not familiar with it, MSSE is Microsoft's nag-free, no-cost anti-virus solution for Windows XP, Vista and 7 owners. Although Windows 8 users can't install MSSE, the utility essentially comes integrated into the OS – it's simply disguised as "Windows Defender". 

AV-Test is an independent German organization who, amongst other things, rates anti-virus utilities based on various metrics about every two months. AV-Test's certification is by no means an industry requirement, but their test results have served as a standardized way to benchmark anti-virus programs for years.

Similarly, AV Comparatives is another firm who offers their own, indepedent anti-virus grading service. After recalling MSSE scoring very high marks with AV Comparatives back in 2009, I checked out the site's latest tests to get a second opinion. Curiously though, MSSE has been missing from tests at AV Comparatives since 2010. Looks like we'll have to take AV-Test's word on this one.