A couple of reasons

1 -  Halo 3 - Halo is the almighty one, and possibly the greatest game to have entered my xbox, if the graphics are gonna be like in the trailer, then the gaming industry will have truly reached a new generation, only on the 360

2 - Fable 2 - I love rpg games, Final Fantasy is my fave, but Fable is also turning out to be an amazing RPG, the two are uncomparable though,due to Fables battle system, only on the 360

3 - Final Fantasy?!?! - The two above are great but by far my fave is Fnal Fantasy, and with news that FF may be ported (I think) Im going to be sleeping outside my games shop for weeks on end, the only stumbling block is the heathenous release dates, i wont go into that cuz ill say naughty words