The ex-ATA 753s are the ETOPS rated ones, they all have E+, no power, no DTV, they have overhead screens. These are the ones we get on the Hawaii routes.
The ex-CO 753s apparently have power as shown in the seat maps, but those aren't ETOPS rated, some have E+, the rest are being converted to E+, they have DTV.
The seat maps on united.com only reflect the ex-CO 753s because of the indication of in-seat power. But if you ignore the in-seat power indication, the version 1 seatmap does correctly reflect the seating layout of the ex-ATA/ETOPS rated 753s.
If you want more detail ...
http://bit.ly/ua753-seatmap, also there's more in the fleet thread.
-David