Read this link! Very good and informative about anti-virus (Must read!):
Excellent sources of anti-virus comparison reports!!
http://www.abxzone.com/forums/showthread.php?t=86202
People's personal experiences & advice are not reliable unless they are really specialise in these fields. There're full of misunderstanding and misconception.
Read some objective tests are the ways to pick your strongest programs:
Here's
an anti-virus program Comparison Analysis from the same author:
http://www.abxzone.com/forums/showthread.php?p=964589#post964589
Unfortunately, it hasn't been updated

, but it should have some uses since past performance somewhat reflects the future.
Here's one website which compares anti-virus programs as well:
http://www.av-comparatives.org/
Fortunately, this one is up-to-date!
This one is good too:
http://www.virus.gr/english/fullxml/default.asp
After all, free anti-virus programs like AVG is still far from perfect Don't expect too much for freebie). If you read the report, you will be astonished that how many malware it misses.
If you are serious about security,
Kaspersky, NOD32, F-Secure, McAfee are about the best, as far as
ONLY malware detection & prevention are concerned (no personal opinions are involved. Just select from the results!). Other aspects like after-sale services, technical support are not considered.
PS: I know pretty users here and there don't like McAfee for varius reasons. However it really offers a very high level of protection. Anyway, this is not the only product in the market. If you don't like it, pick other recommendations.