The version on the US Xbox DVD is already 1.03, though you may want to get the patch if you overwrite your saves, or want to make sure you don't hit a problem with an auto-save. I tend to keep multiple recent saves going as I explore, so generally delete a save a couple instances back if I need to make room for a new one, anyway.
If you are online and signed in to Xbox live, when you start the game it should automatically detect the patch and ask if you wish to download and install it (takes less than a minute).
