MS Windows: the only commercially succesful virus< Unix was chock full of security holes for decades. It's just had more time to close them up. The problem with Windows isn't Windows the OS. It's Outlook Express and MS deciding that email should be in html format, displayed by IE, and running every type of scripting on the planet. That has become the main target. Viruses and trojans attached to files is as old as computers and no OS is immune.