In my college, students were given a free copy of McAfee antivirus version 8.5 (I think) for their computer security. I ran that program on subsequent computers until I made a new computer in late 2008. As a change of pace, I wanted a new program that was free and effective. Out of the many reviews I read online, I decided to try Avira. I currently use Avira AntiVir Personal Free Edition version 9, although I started with version 8 and upgraded from there. The major problem that I had with the McAfee antivirus was that it took up a lot of resources to operate. Scanning my old computer's hard drive was predictably an arduous task for my CPU and memory, but other minor tasks, such as updating definitions, took an unusual amount of work. I wanted a program that would not abuse my new system so much, so I chose Avira.
Unlike McAfee, Avira does not require as much expenditure of energy to run or update. It scans fairly quickly and does not take long to connect to servers to update. The interface is not too hard to navigate, although neither was McAfee's.
McAfee was lacking in some respects in terms of protecting my old computers from threats. Using programs like Malwarebytes AntiMalware and SuperAntiSpyware revealed many bugs that were missed by my antivirus. In comparison, I now use Avira and the two aforementioned programs for prevention and have not had any infections so far.
On the downside, the free edition of Avira does not have as many features as the paid version. It lacks some of the features of my previous antivirus program as well. For example, McAfee had a buffer overflow protection ability, which was meant to prevent a particularly dangerous method of infecting a computer. The free edition of Avira does not have anything this complex to my recollection.
Also, when updating with the free version, a pop up that advertises Avira's products always comes up on my screen. It is slightly annoying, but it is easy enough to close it. There is a way to disable the ad by certain means, but I have not attempted to do so. You also have to register the program occasionally when the license expires, which seems to be about every year or so.
Upgrading from version 8 to 9 was a bit problematic. I attempted to upgrade through a window opened by Avira 8 to download and install version 9. I did so, but upon restarting my computer, the program was not recognized as a working antivirus in my Vista Security Center. Even though it was working correctly by all appearances, my computer refused to acknowledge its presence, indicating that my computer was vulnerable.
To rectify this omission, I downloaded the executable file of version 9 from the internet, uninstalled Avira, performed a clean install of version 9, and restarted my computer. Luckily, my computer finally accepted this method and identified my antivirus program. Although this is not terribly complex to do, it may be inconvenient for those who do not have the time to attempt a clean install.
I would recommend Avira AntiVir to those who are looking for a simple antivirus program to protect their computers. As long as you practice general safety rules, such as not opening unknown emails or visiting questionable websites, this should be enough for basic needs.