I heard the xxxxx virus will destroy my yyyyy. Not physically, not in the sense that you'll have to throw any components into the trash can. Viruses can only wreak havoc on data. There is no virus that has ever crumpled disks, melted processors, caused a monitor to spontaneously combust, put Nair in your shampoo or Rogaine in your Nair. Making my files read-only protects them from viruses.
File attributes can be by executable programs.
Anything an attribute utility can do, a virus can undo. CD-ROMs and write protected floppy disks are safe. True, so long as the virus wasn't already on the floppy before it was write protected or the master CD before it was duplicated. There have been a few cases of viruses making it onto the burn of a major software release, but only a few. One imagines that most software manufactures are religious about seeing that their distributions are virus free.