Beware of pirated executable programs that your friends want you to try. Always insist that they load it on their hard drive first and promise to run the program daily during the viral incubation period. Always scan questionable floppies with a good virus checker before inserting it into your drive orifice. Remember that sealed, cellophane prophylactics around floppies are not always completely safe. At the first sign of a virus, withdraw your floppy and disinfect immediately.
CDs are vulnerable to many other destructive agents.