What is the cheapest and best antivirus software?

If you are looking for the cheapest, I'd actually say NOD32 or Kaspersky. If you are looking for free, I'd say Avast or AVG.

http://www.eset.com/

http://www.kaspersky.com/

http://www.avast.com/

http://free.grisoft.com/

What is the cheapest and best antivirus software?free anti virus

2 good free options are ...

AVG from http://free.grisoft.com

Avast from http://www.avast.com

I personally use AVG

What is the cheapest and best antivirus software?internet security software

Buy anything but Norton....it can totally fry your computer...happened to me and other people I know.
Linux.
You simply can't not have the cheapest and best Anti-Virus software...you get what you pay for. Free or nearly free Anti-Virus programs simply do not off the protection of legitimate companies like Norton's. The BEST you can get is Norton 360 but it is one of the more expensive programs. That's because it's not just Anti-Virus, it's also Anti-Spyware, Active Fraud Monitoring, Back-up and Restore protection as well as Windows and Hard Driver Optimization. It can also be installed on up to 3 different computers at one time so you can share with friends or family.
Avast. It's free, easy to use, upgrades automatically so you stay up to date on viruses, monitors e-mail too.