vista updater not working

if you could post the actual full error message, and which update it choked on.

You could go the the Windows Vista Update site at MS, then run a search, download and install updates manually.

You may have some luck reinstalling the update agent. Do you have SP1 installed?
http://www.microsoft.com/communities/newsgroups/en-us/default.aspx?dg=microsoft.public.windowsupdate&tid=1f153ed7-8081-4715-a18a-fbf64f9a0012&p=1

If you can, reboot and check the updater for error messages by running it again, or checking the logs.