I'm using Kaspersky, it's very reliable antivirus. Start to use Kaspersky Internet Security 2010, the license expired a few month ago and now I'm upgrading to Kaspersky 2011, much better features. Great firewall protection, I love the auto pendrive scan features.

A few week after bought the 2011 version, I just saw the latest version 2012 sell at lowyat.. What the!!!
Anyway you can upgrade 2011 to 2012 for free.