Are there settings within your Netflix account for the default streaming speed/bandwidth for your linked devices? Maybe the xbox defaults to a lower setting? It has been a while since I used Netflix so I don't recall how much control you have over that. Either way, I would expect the newest line of HD Tivo boxes should have no trouble streaming HD quality audio and video on a capable internet connection.Mostly concerned with the video quality. On our son's Xbox, Netflix would rarely display in hd quality. On the Apple TV all the hd movies would display in hd.