A client emailed in this question:
My virus protection expires in about a week. Renewal with McAfee is $79.99 for one year. In your opinion, is this the best (or even a good) option? I know there are a few free ones out there, but I don’t know enough about them.
My answer:
Avast and AVG are both good free AV’s. Here is a link to reviews. Scroll down to the Free AV’s.
All free AV’s try to get you to upgrade to the paid version. Just ignore it.
PS Your email is scanned on our server by Clam AV before it reaches your inbox. That is not 100% but it gets most viruses.
The last note about Clam AV only pertains to certain clients. However, there is also a Windows version for PC users.
Clam TK3

ClamTK3.08” by Dave Mauroni – Own work (own screenshot). Licensed under GPL via Wikimedia Commons.