If you're not sure what you want or need more information, read on. There is also lots of info on viruses at the McAfee site. There is much concern regarding viruses, and rightfully so. A virus is a self replicating computer program written by a person to perform some task. Which means, after your computer is infected by the virus, it will often wait 3 or four weeks before wreaking its havoc on your system.
Benign viruses are few and far between though.
It is safe to assume that any virus you find on your hard disk or floppy drive is preparing for some malevolent manouver. Sometimes overwriting it with a politcal message, or more often, just creating a maelstrom of garbage. This of course is a very bad thing and could be job-threatening unless you have carefull backups of all your important files. This cannot be stressed enough. It also protects you from fire or foreign invasion.