DirecTiVo and UltimateTV units have DirecTV receivers built in. Yes, the datastream is saved directly. There is no MPEG encoder on these units. Only the decoder.

I would urge you to get an integrated solution like directivo. The picture quality will be better, it can save audio in Dolby Digital, and dual tuners is important. I used to only have one tuner on my directivo. As good as Tivo is, dual tuner Tivo is that much better.