http://www.railsinstaller.org is a popular Windows solution for installing the Ruby and Rails environment. However, RUBY_PLATFORM is "i386-mingw32", not "mswin":
irb(main):001:0> require 'rubygems'
Currently, autotest-notification only checks for "mswin", not "mingw". This patch adds checks for mingw, enabling this gem to work correctly on Windows.
Works on mingw platforms.