Hello Donald,
Most cable services supply two different types of DVR boxes, one that records in Standard Definition (SD) and a different one that records in HD. The boxes are generally made by either Motorola or Scientic Atlanta, and the HD versions say so on the front of the box (true of Scientific Atlanta; I'm not sure about Motorola).
DVR recording and playback of HD is normally perfect; indistinguishable from the live HD signal. The storage capabilities for HD programs are very much less than SD programs because of the huge bandwidth demands of HD. My Scientific Atlanta box (Time-Warner Cable) only holds about 20 hours of HD programs. In SD, it will store about 160 hours of programs. The boxes aren't all that reliable. I've had to exchange mine a couple of times because of malfunctions, so check with your cable company on the model of the box and exchange it if it is supposed to record in HD.
Regards,
Alan
