The actual problem is Windows was never designed to be secure. The very foundation of the operating system's design prevents it from being secure.
UNIX is a far more secure platform, but restrictive as to what a user can do. But even with that, there are those who simply log in as root so they do not have to deal with it.
The bottom line is, when it comes to computers, most end users do not have the discipline to operate them in a secure manner. Microsoft knows this, so Vista was a first attempt at taking control away from the user so they can be protected from themselves.