Pro logic 2 is pretty damn good if you have a proper stereo, and as was discussed in the other forum dolby digital does have a slight delay, making games very difficult to pull off. The only thing you hear on an x-box that is dolby digital is background noise and completely canned sound effects. If you like it, watch more movies, I want spur of the moment sound effects based on what I do in the game.
Feel free to correct me if I am wrong, but I have read quite a bit on the subject.