The Reset Glitch hack is pretty much the same thing as the Jtag mod, but it works on almost ALL xbox 360 consoles.
This mod allows you to do the following
1. Play xbox 360 / xbox games from the standard hard drive, or external USB hard drive (no discs required)
2. use up to 2 terrabyte sata 2.5 hard drive as the default drive
3. download and play xbox live arcade games
4. modify games (COD mods, halo 3 map mods etc)
5. install custom dashboards
6. run old school emulators such as the old school NES, SNES, Gameboy, sega genesis,etc.
7. run homebrew applications
8. make your console region free (play asian, european, USA games)