What's the best anti-virus is a question I'm always asked?, but to be honest I don't have an answer because it doesn't matter what protection your PC has I've seen them all infected with something at one time or another. Follow my advice to make your chances of being infected very slim to none.
First off, make sure you do your updates. Update your browser, do your windows updates, flash and java updates are import as well. Most updates are for security purposes, they find a hole in the software then they patch the hole. Getting a virus nowadays doesn't mean you have to install a program or download an attachment, your computer can get infected by just going to a website.
Anti-virus software is important and I highly recommend a paid version of the software. Free anti-viruses don't really help you at the time of the infection, I call them after the fact anti-viruses because they don't do much to prevent you from getting them. Everyone needs real time protection and internet security nowadays. The more strict an anti-virus is the less of a chance of getting a virus. I've had alot of good fortune with AVG Internet Security and I highly recommend it, but if you don't want to spend the money you check out your ISP's website or call them and see if they give you a free full version anti-virus. Comcast/Xfinity gives their customer Norton and Century Link/Embarq gives their customers McAfee, they're both full versions and it's better than having the free ones of any anti-virus.
I've found the most effective software to remove Viruses and Malicious Software is call "Malwarebytes". It is a highly effective anti-malware prevention and removal program. Viruses and malware are getting harder and harder to remove nowadays. You can get a full version of the software for a onetime fee of $24.95. . It's a necessity to have on your computer and I highly recommend it.
So make sure you do your updates, get a full anti-virus program, and buy the full version of Malwarebytes and I know you've done everything to protect your computer and your work. Remember, Don't Pout or Cry, call The Computer Guy 239-768-1600.