You do not need one with Linux.
http://librenix.com/?inode=21

AVG is free and is available for Linux.

http://free.grisoft.com/doc/29124/us/frt/0

avast is another highly recommended for both winblows and linux. I've
only used it on winblows and found it better than AVG - more frequent
updates... often each day.

All three good suggestions. But just to reiterate what deadgobby
said. They are for cleaning Windows viruses. Linux does not have an
environment that supports current viral attacks.

Lets put Linux virus in a preceptive. Linux virus cannot attack the kernel as of
yet. Where as a windows virus can. Linux has so many different programs or
doors. If you do get a virus and if you do. Please share with us. It would be so
rare and the years I have used Linux, yet I have to see one or get one. Windows
i just needed to click on the web and get one. Windows viruses will not work on
linux. Even if you open it with Wine. the program will go HA. Close up and that
would be it. You could send a windows virus using linux to a windows user.