What is the best anti-virus software for Windows 98/XP/Vista?

AVG Anti-Virus is by far the best and easiest anti-virus to install and use and its FREE. It has all the capabilites that
the average windows pc user could need in keeping the latest viruses off your computer. Their are several other all in one
programs like Windows Live OneCare but you’ll have to pay a yearly subscription fee.

Download AVG-Anti virus 7.5 at http://free.grisoft.com