I just read an article on IT World about the latest Windows fiasco with BSODs after installing Windows Updates. There seems to be some disagreement about whether the rootkit was a direct or indirect cause of the problem, but for me that's not the point. What's more important is that we are still discussing security problems with Windows that have been known for 10, 15 or more years?
The point the author makes about the problem would have been fixed long ago in Linux, or any other FOSS software, is the most important part of the article, in my opinion. The way the situation is today, you have a few people at Microsoft trying to keep up with security issues. They may or may not be good - my personal opinion is that they are not - but even if they are, they are hopelessly overloaded and out-gunned. On the other side there are hundreds, thousands, whatever, of very bright, very motivated hackers constantly looking for new and different attack vectors. The result is the mess we have today with Windows.
At least, with FOSS, you have a much larger number of people on the defensive side. The chances of problems being found and fixed quickly are much higher.