By the way, I haven't checked whether this works on Ruby 1.9.3... I am (sadly) stuck developing on Windows and can't install multiple versions of Ruby without RVM.
Be happy...test with multiple roobies on windows using pik: https://github.com/vertiginous/pik
C:\Users\Jon>pik ls
167: jruby 1.6.7.2 (ruby-1.8.7-p357) (2012-05-01 26e08ba) (Java HotSpot(TM) Client ...
187: ruby 1.8.7 (2012-02-08 patchlevel 358) [i386-mingw32]
193: ruby 1.9.3p125 (2012-02-16) [i386-mingw32]
- 193: ruby 1.9.3p235 (2012-06-05 revision 35917) [i386-mingw32]
193: tcs-ruby 1.9.3p231 (2012-05-25, TCS patched 2012-05-27) [i386-mingw32]
200: ruby 2.0.0dev (2012-06-11 trunk 36028) [i386-mingw32]
C:\Users\Jon>pik ruby -e "puts 'hi ruby'"
jruby 1.6.7.2 (ruby-1.8.7-p357) (2012-05-01 26e08ba) (Java HotSpot(TM) Client VM 1.7.0_04) [Windows 7-x86-java]
hi ruby
ruby 1.8.7 (2012-02-08 patchlevel 358) [i386-mingw32]
hi ruby
ruby 1.9.3p125 (2012-02-16) [i386-mingw32]
hi ruby
ruby 1.9.3p235 (2012-06-05 revision 35917) [i386-mingw32]
hi ruby
tcs-ruby 1.9.3p231 (2012-05-25, TCS patched 2012-05-27) [i386-mingw32]
hi ruby
ruby 2.0.0dev (2012-06-11 trunk 36028) [i386-mingw32]
hi ruby