Hi specialbao1
None! That would be my answer:
http://www.linux.com/feature/60208I'm not saying that there is no such thing as virus on Linux, but if you restrict the use of root access to minimum I cant see why you would loose sleep over it.
Have you had any problems with virus for your Linux distro?
If so - just for interest - I would like to know the distro name, and the name of the virus if possible
Kind Regards
Martin Andersen