It's pretty simple, really.. Someone on here took all those e-mail addresses and put it in their address book. Problem is, that person was already infected with the E.Klez virus, and now he's unknowingly spreading it to all of you.
I already get this virus mailed to me almost weekly, have been getting it for nearly 4 months now! I just delete it and keep going, as there's no way to stop it. But Norton does detect it and does a great job in general, much happier with it than McAfee.