I have a friend who has Civ4 vanilla. I have Complete. I would like to play multiplayer with him but he doesn't want to patch his game because he says he doesn't have very much memory on his computer. Is complete backwards compatable? If not, could he move all/part of the game's files to an external storage device, such as a jumpdrive, to save space on his hard-drive or does the game not allow you to do that?