so im just here to tell you a few things you can do with a jtag

-run homebrew..... which pretty much means you can run programs made by you or other people that normal xboxs cant run, an example is an emulator.

-run unsigned code, mod the files inside of a game to create a modded and more fun game.for example tenth lobbies in mw2

- save games to your harddrive, you can do this on a normal xbox but on a jtag you dont need the game to play it so you can run down to blockbuster and pick up a game return it and play it whenever you want

- you are able to unbann a jtag after it gets console banned

- and last but not least you can buy a external harddrvie for a computer, format it to fat32 and use it to save games or other stuff onto it

hope this information helped
also this is purely informational, in no way is this a tutorial. if you are new to jtagging or just need help doing any of these various things listed pm me and i can help you get the best possible fun you can out of you jtag.