Compiling Objective-C for Windows on a Mac?

I am programming an application for OS X, and a friend of mine wants me to make it for Windows. Can this be done? I have two other questions that related to this one, to closely related for me to ask another question.

• 1: Can I use my N开发者_如何转开发ib files to build the interface for Windows?

• 2: If you answered my original question, does your solution work for all kinds of Windows (Windows Vista, Windows XP, Windows 7, ect)?

There's a project called Cocotron that aims to allow you to compile Objective-C for other platforms. It looks like their website says that (for Windows) it works on all NT-based Windowses. I think it allows you to reuse your Nibs, but I'm not sure.

There is also GNUstep and Cygwin, it is kind of ugly, but I have used it in the past. Works on linux too.