I have been thinking about doing the external drive on my Dish 722. Dish says that the max size is a 750gb. But they can't give me an answer as to why that is. Especially since a 1tb costs about the same as a 750gb. I had heard in the past when the 722 first came out that the reason was that the 1tb drives were actually two physical drives of 500gb each and they were just in a case together. But I know that the new drives are not like that. So what can the 722 actually do? How big has anyone gone?