Once upon a time, it was possible to write stuff on the Mac, and have it simply run on a PC. That was back when EOF/WebObjects had a PC version. But I got the impression that Microsoft was not very cooperative with Apple on the endeavor, and it was too difficult to make the cleaner Unix-based design work in the messy Windows environment. The solution was too cohesive, and too susceptible to problems created by every little change to Windows, so Apple dropped it.
It might be easier these days, now that Microsoft is using the CLI as their paradigm.