There's at least one free (gratis) version of Windows available (Hyper-V Server) that's missing the Explorer shell and some other parts. I have successfully in

There's at least one free (gratis) version of Windows available (Hyper-V Server) that's missing the Explorer shell and some other parts. I have successfully installed KDE on this (via Cygwin plus a mesa/llvmpipe build of opengl32.dll). It seemed to work OK.