If you are using Windows Vista in a domain, you may find that Windows Update doesn’t work (it will say something like “No updates available”). This is because when a computer is added into a domain, a registry key/policy is automatically added to connect to a WSUS server for updates.
So to resolve the issue, you need to delete the following registry key:
HKEY_LOCAL_MACHINE > Software > Policies > Microsoft > Windows > WindowsUpdate
Make sure the subkey named AU is also deleted. And finally when done, restart your computer and try it out.
Another way to do it is to change the key (below) from 1 to 0:
HKEY_LOCAL_MACHINE > Software > Policies> Microsoft > Windows > WindowsUpdate > AU > UseWUServer
If all works well, you should get something like this:
Go ahead and install the component and watch Windows Update start working, like so: