Okay, tried this last night.
Was never able to log into medianet unfortunatly. Even after 3 hours of the sim being in the new phone and calls being placed and received on it *shrug*
Did call up AT&T though and say that I was having issues getting MMS to work on the new phone, and the rep worked on it with me for over an hour. He apparantly reset some of the settings on their backend and sent the over the air update.
I shut down the phone and got the update, swapped back to my iphone, and amazingly, MMS worked. Was able to send and receive perfectly.
Bad part now, its gone this morning. Cant send or receive, back to the same error messages I was getting before, so something changed back on my account
Will call up again today and try this again.