It appears that Microsoft Essentials is the No.1 in Windows based Anti virus software followed by Symantec in USA. In worldwide market, MS Security Essentials is followed by Avast.
Checkout the following for details:
https://www.opswat.com/resources/reports/antivirus-december-2012
Well I have a question for all of you Zuneboarders...
Which Anti Virus Software do you think is best...
Options:
avast
Windows Security Essentials
AVG
SUPERantivirus
Norton by Symantic
McAfee
Kaspersky
feel free to list anything I didnt cover