Hi Dee-27
I think your explanation of interlaced and progressive needs a bit of clarification. I will see if I can explain this a bit better. In the interlaced scanning system the group of 288(PAL) lines you refer to are known as a "field" and they occur 50 times a second. When you add the 2 fields together you get a "frame" of 576(PAL) lines that occur at 25 times a second. The same applies to 720i and 1080i there are 720 lines and 1080 lines but they occur at 25 times a second. There is no resolution difference between 1080i and 1080p as they are both 1920x1080. "But" 1080p will look a lot better than 1080i because of the reduced flicker and the lack of distortion effects on motion in the picture because all the lines are scanned at once.