I have used many Anti Virus programs over the years and while the good named ones have their pluses I prefer to use Avast.
There is a free version which is what I use. Like all software out there you can purchase other features or improvements but Avast free version has saved me a couple of time from web hacks that I didn’t know where on my computer.
Please follow this link to get to the software.
Click on the green text – Avast Free software page