As long as the Xbox game you're trying to play is an original disc, you don't need to worry that much. If you were trying to play Halo 2 on the 360, by all means, please do. The 360 is able to play Halo 2 straight off from the first time, without ever needing to update the backwards compatility software. So far, all of the Xbox games I own are already included in the compatibility list... except Rallisport Challenge 2. Why Microsoft didn't bother updating a Microsoft published game is beyond me.