I suspect that if it was included in the Dpaint 4 box then EA do indeed hold copyright on the contents of the disks, and hence the image in question. I doubt EA care, and I doubt they even have details on the name of the artist responsible for the image.
If it was Dpaint 3 you might get a more positive response from Dan Silva but Dpaint 4 had nothing to do with Dan I recall, he left to write some little program called 3D Studio on his own

I'm curious now, does anyone have a copy of this image to link to so we can all see this map?
Perhaps you could ask the nice people at Cinemaware if you can borrow the world map from Rocket Ranger? They will definitely know what you are talking about, they may even let you use it on a free game you are writing provided you credit the source.