No, Windows is not a virus. Here's what viruses do:
Viruses use up valuable system resources, slowing down the system as they do so -- okay, Windows does that.
Viruses will, from time to time, trash your hard disk -- okay, Windows does that, too.
Viruses are usually carried, unknown to the user, along with valuable programs and systems -- Sigh... Windows does that, too.
Viruses will occasionally make the user suspect their system is too slow (see ) and the user will buy new hardware -- Yup, that's with Windows, too.
So, Windows is not a virus.