These results are not surprising. AV is still a valid layer in the IT security onion, but it is far from effective for most threats in today’s landscape.
FortiClient is not the most robust AV / Anti-Malware solution available, but it is free and full featured, meaning it is a good option for endpoints with no protection. Fortinet provides both Windows and Mac versions, providing plenty of client flexibility.
This article should be largely self-evident, but it is very easy for new PC owners to overlook the value of A/V when that trial version expires. This is honestly no excuse thanks to the large number of free and low cost A/V solutions. Microsoft provides a respectable option in Microsoft Security Essentials (http://windows.microsoft.com/en-us/windows/security-essentials-download)