Air Tran uses terminal C and D in ATL. I would stick with the 1 hour connection but once you land go straight to your connecting gate, then if there is time grab a bite to eat or use the restroom. All too often I see people running up to the gate complaining the plane let without them....yet they are holding a bag from McDonalds
They are connected by underground train. Trains come every 60 seconds or so. I couldn't see it taking more than 15 minutes to connect from the farthest Airtran gates.