There are a few completely free anti-virus solutions available from the internet. Something that is even more common is companies having two versions of their anti-virus program, one that is free and still offers good protection and another one that you need to pay for but it comes with all sorts of additional features. I've used the free version of Avg for years now. Back in the day they only had the free one but at some point they did what most do, kept the free version free but also added an option of getting the whole package with a firewall, antivirus and antispyware for a yearly fee. I don't want to pay so I'm still using the free one and to be honest it's good enough for me. It keeps me safe, has automatic updates and overall doesn't bother me unless it really needs to. Low maintenance and works great, so I'm very happy with it. So which one do you use and why?