[quote name='wakawakawa']When you buy a game you get 2 licenses. One for your gametag (must be connected to xbox live) and one for the 360 that it's downloaded onto.
So....... if you are connected to xbox live your gamertag can download and play any game on any 360.
If not connected to live or using a different gamertag then a specific 360 becomes important. You may be able to transfer licenses to a certain 360 (the one he plays on) so your son can play all your games with his gamertag.[/QUOTE]
This is the same thing my wife and I do. For every game I purchase on Xbox Live I take my Gamertag in on a flashdrive to her 360 and make the purchase under my account. This ties it to my tag and her console. Then I go back to my 360 and re-download the game (this makes sure it shows up in the "full games" section which I think doesn't show up in the new dashboard anymore...pisses me off) and then she can play it with the license attached to her console, and I can play it with the license attached to my tag - we can even play the games together with each other at the same time. Only caveat to this method, if my crappy rural internet goes down, I can only play the games on her 360 until it comes back up. This also works for map packs etc. too. And it's a good system for MS, because I have bought co-op games I wouldn't of normally just 'cause I know I can play them with her. Sorry for length, bring on the TL;DR's.