Which Anti-Virus do you use?

[JoeW1982]

paid : kaspersky
freeware : avast.

Drawbacks of FREEWARE AntiVirus Programs.
AVG and Avast have poor detection of polymorphic and 0-day malware in addition to having limited self protection.
The free Avira lacks an email scanner; that's only available in the paid version. The self protection is also poor - it can be terminated with Windows Task manager. The free version also constantly nags you to upgrade.
The Kaspersky-based AOL AVs lacks the html scanner found in the full Kaspersky product and consequently doesn't offer the same level of protection against hostile sites. It's also quite heavy on resources and is not suitable for slower PCs. AOL AVS can be terminated by a hostile agent as well

BitDefender lacks a real time monitor as well as email scanning.

SOURCE : http://www.winvistaclub.com/etc.html

[Phoenix]

I used Kaspersky and Panda quickmover but it didn't worked good for me. Later I have found Nod32 and I'm using only this antivirus program now.

[Steve-o]

Clam A/V, works wonderfully for email & web. Also highly rated as most up-to-date virus definitions.