We live in an RV fulltime and have a standard 2 LNB Trackvision Dish on the roof of the unit. We need to replace the DVR in our system and I would like to upgrade to the HR20-100s DVR. We have upgraded the TV to a HD 1080I. My question is will this DVR work until some furture time when I upgrade the Dish? I understand that I will not receive HD, but will everthing else work correctly?