Well bud before you do anything learn how to code a win32 GUI... pure DOS applications (not win32 bit console applications) are written in 16bit code. now, when translating them into a win32 gui, you will loose percision and have errors.
So the fact is learn how to write win32bit GUI applications, with the WINAPI or MFC, then rewrite your DOS code in the new program.
its that simple..
the DOS GUI and the WIN GUI, are just front end code...
so what ever DOS GUI you did is now garbage.
your back end code should be very easibly ported for the WIN32 environment.
Im guessing you are new to C++ on a windows system?