If anybody asks me for recommendations on an anti-virus solution, I always point them to AVG. I’ve used it for years and love it. It has a great UI, does a good job detecting and cleaning viruses, and they have a free edition to-boot! The only drawback to the free edition is that it’s so hard to find the download!
If you do happen to download and/or install the not-free version, it will prompt you to convert to the free version when you go to uninstall. So that’s another way to get it.