The update system has never been the strong suite of Windows. I suppose everyone remembers fondly the pop-up dialog windows of XP prompting you to restart that came back right away when you closed them. The Windows 7 version is similar but at least you can specify a 4 hour grace period (at most) until which time the notification does not come back to pester you.
What happened today on my work PC was really annoying, though. I was happily typing away closing in on the end of a paragraph, ready to smash ‘Enter’. At this precise point the god-forsaken pop-up reared its ugly head and it stole the focus from the then current window. As a result my ‘Enter’ went to the default selection on the dialog window, which was, you can probably guess: ‘Restart now’. I could only watch helplessly as the system closed down all my open applications one by one, severed the remote desktop connection, and commenced updating itself.
I understand the problem that users are reluctant to restart to update so they need to be educated, but really, dear Microsoft, really, a focus stealing pop-up? Do you call this UX?