I'm currently running RADIANCE on Cygwin, but previously used MS
Services for Unix. I ran into a few weird compatibility type problems
with SFU (I don't remember the specifics now) and in the end decided to
switch to Cygwin because it seems to be better supported (for other Unix
type tools as well as for RADIANCE).
I've also previously made a comparison between Linux (Suse) running as a
virtual machine under windows (using MS Virtual PC) and Cygwin. Using
the test case from Mark Stock's benchmark page I found that Cygwin was a
bit faster than the virtual PC (something like 15-20% faster) - at least
on my specific PC for that specific test case.