So far I see that all the HD channels coming from the HD box are in 720p. My HD box is a Motorola DCH3200. I downloaded the manual for this box from Motorola's website and discovered something interesting. The manual has a section called "OPTIMIZING YOUR DCH RECEIVER FOR HIGH-DEFINITION TV". This allows you to get into the box's settings example:
User Setting Status - TV Type: 16:9, YPbPr OUTPUT 1080i, 4:3 Override 480i
This setting seems to be geared to the Component Video but I'm using HDMI. Later I well hook up some Component Video and see if I get the 1080i as indicated. I'll keep this thread posted as to the outcome when I do.