Terry, there is no need to reinstall iGuidance 4 just to get out of the full-screen mode. As inav says, just press the F-key on your keyboard to get back to windowed-mode. F-key is the hotkey that toggles full-screen mode. The new iGuidance 2009 will be more intuitive, as you will see the 'Full-Screen" button right on the screen (even in the PC version, not just in the UMPC version).
You will be able to access GPS setup options via menu toolbar, after you exit full-screen mode.