look for lindows. they're doing something kinda like that. nobody is sure if it is for real or not though. basically they're copying it very closely as a theme on KDE (a linux "gui"). presently, you can't wine explorer.exe (at least, last time I tried), but if you could, that would be a step to perfectly copying the GUI.
edit: wine emulates windows so you can run windows programs under linux. thats the simple version. it doesn't really emulate, but i dont feel like explaining, and its all on winehq already 😉