I am sorry to hear about your loss during the hurricane. I hope you are enjoying Georgia for the time being. Air Tran flies between Atlanta and New Orleans and Gulf Port. They actually have a sale going on now, but do have some black out dates. It might be worth calling the airline to see if they are offering any type of discount to Katrina victims.
Amtrack also goes between the two. From what I could see it is about $58 one way per person.
I hope you can find a deal!!
Julie