I tried the free version of AVAST a few years ago, and it seemed to work fine. I did however think that it was a little on the heavy side of resource hogging. And even though it had the ability to have it's actions suspended, I still found it stealing some resources whenever I checked the task manager. I couldn't shut them down completely. I would look, and yep, there they would be, AV something or the other, still running. So after going without for a while, and doing my best to surf smart, I decided to go back to using another anti virus software. I went and purchased the Kaspersky product. It has some pretty good reviews and seems to work as advertised. I like the fact that I can completely shut down all of it's functions when needed and start them back up just as easily. So far, I feel as if I've made a good choice.
Nutz