I would believe as you said that X & Y are the placement values and W & H represent Width & Height. At first I would be skeptical like you that such a small number wouldn't make for a fullscreen image, but after my dealings with modifying the sizes on the fly on my tv, I know that in the lower resolutions (480i/p) that it probably wouldn't have to be very big at all to be full screen. My reasoning for that is when I switch to 1080i, my screen size only takes up a tiny portion in the upper left corner. Once I finish stretching it to fill my screen, the numbers end up as something like 2,000 X 1,100 or something. At first I thought it should resemble something closer to 1,084 by 768, but I'm assuming that the screen size #'s might not neccesarily represent a true resolution. With that being said, my 2,000 X 1,100 size at 1080i is about 10x bigger than my normal 480p settings, so according to that my normal size is 200 x 110. Go figure.