Vista - XBOX 360 with Windows Media Center Error

So I have searched and searched these threads, but no one seems to be getting
the same error message I am.

My 360 is hooked up fine, I can access XBOX Live fine, and the XBOX is
hardwired directly to my router. Also my computer is hardwired from the
router, and my computer internet works fine, so I know the router is
functioning fine.

On the XBOX I went to "Media Center", got the 8 digit access key, then on
the computer opened Media Center, went to "Tasks", "Add Extender", typed in
the key... but during the setup I get the following error message:

"An error occurred while configuring extender settings. Restart your
extender and computer and try setup again."

grrrr so frustrating. any suggestions would be greatly appreciated. Here's
what I've tried:

*Running it with firewall turned off. No luck.
*Connected XBOX directly to Modem (no router). No luck.
*Ran Media Center as administratod. No luck.

I've read it may have something to do with "group settings"?? or my computer
belonging to a "domain"?? hmm unfortunately I don't know what those mean lol.

Please talk to me as if I'm a 5 year old haha, I may need a little extra
help. Thanks so much!

--josh--