I've just run across these two projects in the last few days.
"Windows Update Downloader"
also known as WUDhttp://wud.jcarle.com/
At the forum, there is also a little program called UpdateHammer that looks promising for integrating for automatic installs.http://www.msfn.org/board/index.php?showforum=147
They also cover slipstreaming.
Nice wiki with pictures that are of the more recent version:http://michaelboman.org/wiki/index.php?title=CTUpdate
They say this one doesn't download all the updates, but the most important ones for security. It creates an ISO for burning with an auto run for installing.
Each one has their own pluses and minuses, but they're better than nothing after reinstalling Windows. They also include some Office Updates.
I've tried them both for downloading and archiving the backups I need. So I now have backups current to the end of 2007 and every 2-3 months I plan to get the new ones to stay reasonably current. I have not had the opportunity to try out how they work to install yet; but if push came to shove, all the updates could be manually installed individually.