Ok, here is my 2c.
I play WoW and try to get the best latency possible.
Kaspersky and NOD32 both added about 100ms to my latency, after trying to tweak it and whatnot, it still affected the game so I ditched it.
Then I tried BitDefender and it worked 100% with no impact on my WoW latency.
Unfortunately, BitDefender 8 (which I bought and is licensed till August this year) does not work on Win 7.
So I am using Avast in the meantime, which also does not affect my latency.
Warning to AVG users
A girl in the office had her Gmail compromised and sent out spam to all her contacts - she was using AVG.
I then explained to her that AVG does not offer protection against keyloggers, which she most likely picked up.
I grabbed the following from Wikipedia:
According to AVG Technologies, over 80 million users have AVG Anti-Virus protection, including users of the Free Edition. On April 24, 2008, AVG released AVG Anti-Virus Free Edition 8.0. Along with a more colorful interface, the new program added some new features - a combined Anti-Virus and Anti-Spyware protection engine, LinkScanner Search-Shield safe search protection, plus the AVG Security Toolbar - which were previously only available in AVG commercial versions.
There are some limitations with AVG Anti-Virus Free Edition 8.0 compared to the commercial versions of AVG products. These limitations include:
* Less protection - AVG Anti-Virus Free Edition 8.0 provides only base level protection against viruses, spyware and safe searching. It does not provide safe surfing (drive-by download protection) nor protection from crackers, keyloggers, spam, phishing attacks and malicious file downloads that can come through instant messaging and attachments from seemingly friendly sources. This protection is only available in the commercial versions of AVG products.
Not 100% sure if Avast blocks all keyloggers, but at least it does protect against some.