According to Jesiatha downloading the front end for Live Arcade wasn't possible for Xbox.
Besides, MS plans seem much more exquisite for XBox 360. Live Arcade will work much better with the new front end. Being able to set up games with people will be so easy with the new guide system. Plus this gives MS time to flesh out their plans more with Indie developers. Remember Live Arcade just isn't for replaying old games.
I've been thinking about it, but where will 2D developers go in the future on consoles? They can't compete with these expensive cinema style games. What if companies like Treasure start designing brand new 2D games available for download over live arcade?
Give me Guardian Heroes plzzzzzzzz thx.