This is my opinion so you can take this comment with a pinch of salt but apart from MSE I find anti virus programs problematic and a lot of the time unnecessary.
A lot of the time avoiding viruses involves common sense in the fact that as long as you are visiting dodgy websites and download anything with a big green download button on it, you will probably be safe without a real time anti virus, obviously they can help but I find they cause more harm than good, sometimes viruses can get through but using a lot of common sense is mostly enough to avoid them.
You can invest in an anti virus program by all means but I don't bother with ones, especially paid ones (Although I do recommend MSE).
