First off, anti virus protection begins with YOU, and others who use your computer.
How you use the internet & maintain your computer starts with yourself. Combine that with an excellent anti virus program below:
Eset NOD32 Anti Virus $39.99, I use this personally, excellent protection for my use last 2.5 years. Very low on computer resources, no impact on computer performance as other anti virus programs very well do.
Other top leaders in anti virus protection are –
Bitdefender Anti Virus, Kaspersky Anti Virus, Eset Anti Virus, Avira Anti Virus and Avast Anti Virus.