A matter of degree, not principle (Score 1)

Of course nobody can argue that any hypothetical vendor standing in the place of Microsoft (i.e. Apple, Red Hat, etc.) would not have any security issues, and all of the arguments about security problems caused by users and the ever-evolving ingenious malware authors are valid. However, my view is that the problem that has dogged Windows through it's whole life is that so many of the most serious security problems are inherent in the underlying architecture, and so they cannot be fixed without making significant alterations to the architecture of the system and hence obsoleting trillions of dollars in sunk investment in hardware and software.

Many of the potential alternatives to Windows do not have such fundamental problems. They have security problems, and always have, to be sure. But these problems can typically be solved without breaking the system, or the architecture is such that it can be modified without disrupting applications software and other higher-level entities in the system (i.e. these systems are more modular).

Windows seems to be a poster child for the problem of saving time and money by rushing to get a system out and deployed as widely as possible, before all of the security issues and concerned have been thought through and/or discovered. Once so many systems are out in the world, your hands are tied where making big changes is concerned.