Does anybody know if video quality suffers by setting the video settings on the Tivo to Fixed 1080i? I've tried it that way and at Native. It seems that some HD channels are 1080i and some are 720p, and that all other channels are 480i. My TV supports all of the formats. They look fine, but I don't care for the flickering from the Tivo when I change between video formats. With the setting on 1080i Fixed there is no flickering and the picture looks good, but I don't know if I'm actually getting a worse picture by doing that because of any conversion that the Tivo has to do. I'm mainly concerned about this if it's converting 720p to 1080i. Is anybody knowledgeable about this? Any advice?