Windows NT 3.51
A few useful links
NTShell was originally an attempt to port Calmira LFN to Win32 (Windows NT 3.51), but I ended up writing several parts from scratch, specilly the file manager (I never liked the way it is implemented in Calmira, I hate the fact that the Recycle Bin and My Computer are just windows instead of "virtual" folders) and the desktop (so now it is a ListView instead of a bunch of minimized windows). Also, I've added a number of improvements, taking advantage of the fact that in NT there isn't GDI and USER 16-bit heap limitations (more bitmaps and windows).
I also discovered in the internet an amazing library called madHook, which allows me to hook API functions. Using it I hooked several NT "stubs" and implemented them to some extent, like the Tray functions (to implement Win9x/NT4 system tray behavior) and icon-related functions (to enable the use of 256-color/32-bit icons).
To run NTShell you are going to need an updated COMCTL32.DLL and IMM32.DLL. You can get both here (in NT 3.51 section).
But be careful! Although NTShell works well and stable for me I do not guarantee anything.