I have a samsung le 37r 88bd tv which is 720p hd ready.i have skyhd and a ps3 connected to it as the tv can accept a 1080i signal should i use that to watch sky and blue-rays or have it set to 720p as that is closer to the screens resolution.
Every tvs different. Try them both for a week or 2 to see what you think. With mine, I found the picture looked slightly better with 1080i, but it can judder a little. Whilst 720p was more stable, but not 'quite' as detailed looking
your sky box will have an auto setting on it that to my eyes produces the best results, but it is very marginal. This setting changes the output depending on what your watching, 576p for SD and usually 1080i for hd.