Since you are running Windows, I recommend the Microsoft solution "Microsoft Security Essentials".I couldn't even run basic windows updates, was interesting problem. Guess I'll look for different Antivirus, since AVG and Norton have been retired.
I am using that for several years now and never had a problem with it.
As long as you don't download software from "getadobeprogramsforfree.pirate" or similar, you should be fine.