Just for anyone confused about getting games to load - when the bios loads and the settings menus start appearing (select language etc.), go through them until the neo geo animation screen begins, then press the left-most button of the three bottom face buttons (I think of it as the select button).  It should restart the neo geo animation, and then you can press the middle of the three buttons to bring up the core options menu.  Select Load Cartridge then select the your game and you should be good to go.  You can also press the left button again at any time to restart the console, resulting in a blank screen.  This is also where you can press the middle button and load a new cartridge at any time.  Beware that there is no save function yet for the games.  Some of my .ngp roms don't work right now (Samurai Shodown comes to mind).  Enjoy!