This tutorial will show you how to get Xbox original games running off your Jtag/RGH hard drive without any compatibility errors. This works by downloading the game ISO from the internet and extracting it onto your Jtag hard drive and by copying the game from a disk to the hard drive.
Xbox Original Games: http://www.xbox360iso.com/xbox1-game-downloads-f35.html
Xbox360 Backwards Compatibility: http://support.xbox.com/en-GB/games/xbox-games/play-original-games
HDD partition fixer plus Xbox 1 emulator: http://www.realmodscene.com/index.php?/topic/35-how-to-play-xbox1-games-on-your-jtagrgh/
Xbox Backup Creator: