This is how to get autotest in colour on a windows box.
First of all ensure you have the win32console and term-ansicolor gems, and obviously zentest.
Then if you don't have the file .autotest in the root of your application, create it and put the follwing require into it
require 'Win32/Console/ANSI'
and viola! lovely coloured specs, not as nice as youd ghet on a mac, but if you have to put up with windows, it makes life that little bit nicer.