Sorry for the n@@b question but my head is starting to hurt from attempting to assimilate tons of new info. I want the HR20 with a built-in DVR. Is this model called the HR20-700? Is this currently the only one that DTV will "sell" me? Are other variants of the HR20 (e.g. -500, -399 etc.) available? Are they any good? Is the HR20-700 the current state-of-the-art? Thanks for the help!