I bought the GOTY edition and it seemed to download into my windows7 computer with no problems. I played through the game and completed the "take it back" quest and the game ended. No "Broken Steel".. nothing. I tried all the endings I could.. but the game ended no matter what. This leads me to believe that the DLC content is not activating for some reason. I checked the game folder and all the DLC content seems to be there. Any help would be greatly appreciated.

Did you activate the DLC under the data files tab on the launcher?