well the tv shows will be streamed to your 360. In order to dvr them, you save it to your Hard Drive. They mentioned in the major nelson interview, that some providers will offer on demand services. Your current xbox 360 can handle all of this. The only thing needed is a model with a hard drive attached if you want to have the dvr services. In theory, the 20gb one will do. (My comcast one is 20gb, and it barely is close to full) but if you don't watch your shows in a timely manner, record a lot of shows, and/or dl a bunch of stuff from the marketplace then you will need a bigger HD.