From SeatGuru:
http://www.seatguru.com/airlines/Del..._737-800_A.php
Delta's Boeing 737-800, coded 73H, have personal TVs and USB ports at a every seat. All other 737-800s, coded 73Y, still have overhead TVs in both cabins. Delta is in the process of converting all 737-800s to 73Hs.