What is the world's #1 anti-virus software? (one shareware and one freeware)?

Is it Kaspersky for shareware category

and Avast! for freeware category?

What is the world's #1 anti-virus software? (one shareware and one freeware)?windows

AVG Pro and AVG Free :-)

What is the world's #1 anti-virus software? (one shareware and one freeware)?antivirus download

Both the company I work for and the college I go to use AVG. You can download a basic version for free, and it doesn't add all the extras on to your computer and slow it down like Norton 360 does.
You are right:

Kaspersky - best antivirus.

AVG - Free antivirus.
I use AVG Free also
In popularity and sales (there is just no accounting for some people's gullibility):

Norton - shareware

AVG - freeware

In protection and usefulness:

Kaspersky and Nod-32 (tie) shareware

Avast! -freeware