I have a 60gb hard drive so I decided to download cod4 to it as I have 1 copy of the game and 2 xbox’s ( one is my sons ). I thought that way I could play against him without the expense of buying another copy. It downloaded, and used 6.7gb, but when I go into my saved game data and it gives me the option to ‘play game’ it says insert disk. I thought I might be able to put the disk in just as proof of ownership then eject but this just returned me back to the dashboard. Is it possible to play a game from hard drive or am I wasting gb’s? And whats the point of downloading, if not?