I don't know. I suppose it's a step that's somewhat forward, but it's mostly sideways. Now you've just created a new set of security holes to find, really. It's sort of like going tothe doctor and telling him that "it hurts when I do this" and he responds with "don't do that". Sure, it's an effective solution, but it's far from optimal; it just avoids the problem instead of fixes it; it just remedies the symptoms, not the disease. (Would you like me to find another way to put it?)

Of course, the problem is that MS's security holes result from the lack of (or poor) design put into Windows, et al., not just bugs, which makes fixing them remarkably harder.

On the other hand, you're right. MS is to be commended, if only slightly, for attempting to do something to solve the problem. At the same time, if it was your car, and the problem was that people were taking it for joyrides, the manufacturer releasing a solution that tried to determine who was an appropriate driver or not by pattern recognition wouldn't be met nearly as well as if he provided you a lock.