Need anti-virus? Cheap? Check out "Avast!"
Avast! is a free and lightweight antivirus protection software, that works fantastic and boasts: "avast! Free Antivirus is the best virus and spyware protection available." Avast! Boasts over 130 million users worldwide and has recently been rated the fastest scanning anti-virus in the world at 16.3 MB/S (Next was McAfee with 11.2 MB/s).
In terms of its use, avast! is free and highly secure, only asking that you register it once a year for the free version. It is constantly on and making sure that you are safe, but only using a VERY small portion of your computer's memory. Should you stumble upon a site that has cookies or files that will harm your PC, avast! will immediately pop up with a warning, blocking the page and informing you of the risk. It also does a great job with programs, allowing programs that could be dangerous to be run in a sandbox mode, allowing you to run it without risk to your PC!
My personal rating would be a 5/5 due to ease of use and how well it protects my PC. (I have been using the program for 4 years without a virus). If you are already using a free version of another software, or looking at switching to a free anti-virus, you should really think about installing avast! on your PC.
Visit Avast!'s main website at http://www.avast.com/free-antivirus-download