First - My Panasonic 37" plasma (TH37PX60U) is connected to my Comcast DVR/HD box via HDMI. My options for the setup on the DVR for the display are 720p or 1080i - what's the difference between the two? I'm not sure I notice a difference. When I think I see a difference, it might be my mind thinking it's seeing a difference. What should I be looking for? Second - With HD broadcasts, why is the quality so different sometimes? It usually always looks great with Discovery HD or INHD, but sometimes the other networks vary quite a bit. Saturday night, I was switching between two college football games, one on ESPNHD and another on ABC or CBS HD. The ESPNHD broadcast looked much better than the ABC and CBS games in high-def. Why?