If there are lot of windows 2000/Xp/etc. system in your network and all run schedule update, not only it eat some of your bandwidth but also same update file will be downloaded individual by every systems. If you have a windows domain server that can handl the centralized updates. This is an alternate way with caching.
Even though Squid do a good level of caching with refresh pattern for the specific domain/files. I found Squid + Jesred + apt-cacher is better. By using this we get update as it from local. In my previous blog i put how to use Caching deb package using Squid cache proxy and apt-cacher. With minor cahges to this will make to cache windows update also in apt-cacher.
New rules in jesred
The jesred will work for Windows updates with these changes.
in abort files
in the redirect rules
regexi ^http://((.*).windowsupdate.com/msdownload/(.*).(exe|msi))$ http://127.0.0.1:3142/\1
regexi ^http://((.+).download.windowsupdate.com/msdownload/.*)$ http://127.0.0.1:3142/\1
Note : I found HITs are not recorded as HIT in the “/var/log/apt-cacher/access.log”