I will say that Tivo's software and user interface is much better to use than the cable-company supplied DVR. I have an original series Tivo that we use to watch the majority of our TV on and a cable company supplied HD DVR (SA 8000HD) to record HD material on and have to say that the Tivo is highly superior in terms of ease of usage. Of course, I can't tape HD on my Tivo so no choice on that matter ... :)
The last I had heard, guys, was that DirecTV was going to stop outsourcing their boxes - they're all going to be made by DirecTV. So in the near future, no more Samsung and Sony DirecTV boxes. The DirecTV HDTivo, BTW, is scheduled to be released on April 13th.
Masaki