I use the free version of avasti Antivirus and it seems to be working out real good,
Along with that I use "IceSword" an anti Rootkit software, it is great!
And I run "RegRun Reanimator" on my computer, it runs at boot up and is great for rootkits, etc.
I was using just AVG, but that is how I caught  a Virus/Trojan, AVG didn't catch it. I almost had to wipe my hardrive before I found out about IceSword and RegRun Ranimator and then avasit

PoserPro 2014, Windows 7, AMD FX-6300 6 core, 8 GB ram, Nvidia GeForce GTX 750 Ti