I use clam to root out windows bugs, but I have no worries about any wild linux viruses. After a little snooping I found info on 3 Viruses found in wild that infect old apache/Openssl, but nothing that can get through a modern kernel on a limited account. Don't surf the web as root and you need only scan to protect your unfortunate Windows using buddies. Now If sombody knows you use a particular kernel, and convinces you to download and install a root-kit you can get zombified. So don't install crap from people who know you,don't like you much, and can hack with some skill.