the second is that you may need to configure your att router to do port forwarding. does it show up on http://portforward.com/
i say 'may' because i don't know whether your att router is just connecting your computer to the internet, or if it's filtering incoming connections by default
i would suggest to unclick the "try upnp" button in vidalia, since your router doesn't seem to support it,
and then try to allow incoming connections in your software firewall, and see if vidalia likes it. meaning, see if the log messages in vidalia say that your tor found itself reachable.
if so, you're a winner. if not, you'll need to work on the at&t router part of the equation.
man, i wish port forwarding were easier.