Um, I don't know how to tell you this. You shouldn't be upset.
Linux doesn't need anti-virus. Virii have a real hard time spreading on a Linux system. Your days of worrying about email worms or dodgy attachments are over at last.
However, if you're using it as a server for windows boxes, it would probably be a good idea to have a virus scanner installed to sweep the shared docs. Any of these is fine:
Kaspersky (not free)
www.avp.ch
Bitdefender:
www.bitdefender.com
I run bitdefender on my samba server, and its found all the test ones I placed there (I have a nasty habbit of saving them on floppies when I clean out a system)