The desktop is 800x480 but you have to take into account the menu bar at the top which is about 45 pixel down and the program bar on the left which is about 80 pixel from the left. I say resize your picture to 800 by 480, cut it, then drag it 45 pixel down and 80 pixel to the right then paste it and save it. Then it will come out right. My desktop is mostly covered up anyway I can barely see anything behind it.