A while back, Microsoft announced that the 360 would have some level of backward compatibility. Today Bungie revealed that both Halo titles will work on the Xbox 360, with no alterations, just use your old games and plop them in. The only difference will be the somewhat better quality on HDTVs due to it being widescreens and higher rez. Halo's splitscreen and Halo 2's multiplayer modes are still functional as before. Read more details over at Bungie's Halo 2 Anniversary Special.