Dear programmers

Can somebody tell me how to convert Linux exe ( compiled by gcc) to windows exe
I have made an application where I use Linux frontend(ie QT 3.1) and exe files of linux(unix)
But now I have been told to make the same application with windows frontend.
Frontend part I will handle with QT for windows but how to port these linux exe file directly to windows platform.

In fact I tried to compile the same in C++ compilers but lot of errors are given. Where as with gcc on linux platform it easily compiles and gives the exe file.

How can I use this exe in windows.( that's why my question above as to how to convert Linux exe ( compiled by gcc) to windows exe