Do you have all the original files and roms? If so then you can either burn a DVD-R and use the harddrive loader or FTP them back to the xbox. If you burn a disk, there won't be enough room for all the roms ( if you have them all). When you use the harddrive loader it will send the folders to their correct locations and then you can just FTP the remaining roms to the rom folder. Here's a link for the Mame X emulator : http://www.megagames.com/xbox/xbox_emulators.shtml#MAME-X
