Thanks very much - got it going.
Now - can you tell me why when I make a background of 1024x768 in Photoshop, load it into Screen4 it looks correct. When I load it into Mach3 it's WAY bigger than it is.
Also - it says somwhere in the doc's that transparent can be achieved using 24bit RGB 245,245,245. PS only offers 8,16,32. No transparency for me...?