Is there any particular reason that you are using Vidalia rather than another more documented setup?
What do you mean "a more documented setup"? Vidalia is the official TorProject GUI for tor. I am using it, because it is the best GUI interface I've found to tor, and has never caused me any problems before.
Adding a proxy (that I don't need) wouldn't fix the problem of tor not working, it would just complicate things and make it harder to debug.
Anyone have any ideas why Tor might think it is working, and not throw any errors, but fail to anonymize my traffic, given the network setup I mentioned above?