I had an issue where even that (or manual registry changes) would not get the updates to move.
To solve it, I had to use a utility called WSUS Offline Update:
http://download.wsusoffline.net/
That will analyze your system, download the updates you need and forcibly install them even if Windows doesn’t want to cooperate :)
I may have to do this with my wife’s Vista computer.
CPU usage often goes to 100% when windows update is running and makes it nearly impossible to do much of anything else on the computer. It’s an older laptop with a single-core Sempron.
Sometimes I use Belarc Advisor to see which updates are critical, and just download them manually.