|You can't anyway run Turbo C++ 3.0 in full screen mode under Windows 7 since a DOS/Win 3X application is not allowed any more to set that mode under Vista or Seven.|
Graphic mode in legacy Borland applications is limited to VGA mode (640x480) so forcing full screeb under NT environments. Here why you can run that in safe mode only, because the emetgency startup runs as VGA interface.
The way to workaround is to download from Microsoft MS Virtual PC (free), setup a virtual machine with DOS as guest OS and install Turbo C++ inside the virtual environment.
You can get a free DOS from www.freedos.org, an Open Source clone of MS DOS.
The process requires a bit of work but it is not hard and satisfaction is full. That way your graphic applications run in a window as other Seven programs.