Because of the sheer numbers - Microsoft I think, do enforce urgent security fixes - even if you have chosen to select the download and notify me option.
This is confusing.
The experts will be able to confirm this. For non business end users.
Win 7 Pro does not behave in this way. All 5 of my systems here run it, and are set up exactly as I want. The kids PCs update important stuff automatically. The other 2 PCs & my laptop - I'm like Keef: Notify, pick and choose, then update when I'm good and ready.
I can't speak about Win 7 Home or Vista, but I'd be surprised if they are very different.
SD