I've done some more modifying of sys.txt and found the following:
If I set screen_x=800 and screen_y=480, iGO starts up and gives the options under Tools/Display to select from ALL the skins in the skins folder, HOWEVER on my screen I have a system status bar at the top, and the navi screen is pushed down by the amount of this bar, making the buttons at the bottom only just visible, and only the tops of those buttons.
I'm searching the forum for the solution, I know I saw it somewhere !!!!!