I believe Avat's virus vault just contains viruses similar to any other AV's like nortons vault (but 10 times better). I always just choose to delete the infected file though. Never really looked into it, but there really wouldn't be any point to putting WoW in the virus vault because either way if it is in the virus vault or not, Avast! will detect the malicious code. Your WoW is already protected from keyloggers
Unless it is a rootkit, which really the only good protection against rootkits is say I believe Norman was good against rootkits. I had a conversation about it a while ago, on a different forum which has since then made a new database so the threads were lost.