There are several good free antivirus programs. On my 64-bit Win7 laptop I now have AVG Free, with the basic components. Since Avast Free now can be installed in Compatibility Mode with other AV products, I installed that after AVG, and left out the Email Protection Shield, since I have it on my AVG. I just installed the components that I needed on each program. I also have Agnitum Outlook Pro Firewall for additional protection.
The combination works only on my 64-bit laptop. When I tried the same combination on my WinXP 32-bit desktop computer, the AVG could not be loaded in combination with Avast, and I therefore only use one AV: Microsoft Security Essentials, along with the free Emisoft Online Armor Firewall. I seem to have enough protection with that combination. That computer is not used as much as my laptop.
I read about the failed tests and was surprised that Microsoft hasn't upgraded their MSE. According to a recent news article, Microsoft has already been hacked. Perhaps they are not concerned with Windows XP or 7 anymore, since they came out with Windows 8, which does not require MSE and has other security built into that program.
That is a shame, because I really liked MSE. I decided to uninstall it from my Windows XP computer. I wanted an AV that was compatible with Online Armor Free Firewall. AVG would not install with OA, and gave me a blue screen. Avast did install, but it would not start, even when I registered it. I ended up uninstalling OA and attempting to reinstall AVG and Avast separately, with the same result. I was able to install Panda Cloud and then did a fresh reinstall of OA. That combination worked fine, and I believe I have better protection than with the MSE in its current state. I am hoping that Microsoft will make improvements in that software to bring it up to the highest standards.
There are several good antivirus programs. Bitdefender is another good one, bit it slowed my Windows XP down, and I was also unable to shut that computer down. It could have also been the combination of BD and OA that was causing the problems.
If you have an XP 32-bit computer, and want to install AVG 2013 Free, you will need to make sure it is for that computer. Otherwise, AVG will download the 64-bit version for Win 7. I made that mistake and had to install Panda. I had to use the Panda Removal Tool and CCleaner, then uninstall my Online Armor, before I could install the AVG 32-bit version from File Hippo, which has versions for older computers. Then, after installing the correct AVG, I was able to reinstall the Online Armor Firewall. So, now I have two different versions of AVG on both of my computers. Just a tip that might apply to other free antivirus products.