Until now it seems Windows is a virus but there are fundamental1.They replicate quickly - Okay, Windows does that.
2.Viruses use up valuable system resources, slowing down the system
as they do so - Okay, Windows does that.
3.Viruses will, from time to time, trash your hard disk - Okay,
Windows does that too.
4.Viruses are usually carried, unknown to the user, along with
valuable programs and systems. - Windows does that, too.
5.Viruses will occasionally make the user suspect their system
is too slow (see 2) and the user will buy new hardware. - Yup,
Windows does that, too.
differences: Viruses are well supported by their authors, are
running on most systems, their program code is fast, compact
and efficient and they tend to become more sophisticated as they
mature.
So Windows is not a virus; It's a bug.