I had a problem with Windows update when I deployed a batch of new XP workstations not long ago. If you are receiving error 80072efd here is how I fixed it.

1. Verify the problem and see the error. Go to windows update and click custom or express install.
2. Turn on proxy settings in browser. - set ?your proxy server name? and port 8080. Using firewall client is not good enough - you have to set this to fix the issue
3. At a cmd prompt run proxycfg - you will see something about direct access?
4. Run proxycfg -u this will import the browser setting into the registry correctly.
5. Go back to the browser and back to windows update. It should work now. It should even work with the proxy settings turned off in the browser if they have proxy client installed.