+2  A: 

Watir only works with 1.8.6, as far as I know.

Vapir (updated fork of watir - see http://vapir.org ) works with all recent versions of ruby.

Ethan
A: 

To allow Watir (and FireWatir) to run on ruby 1.9.2 install devkit and follow procedures listed here : http://rubyinstaller.org/downloads/ Ruby Installer at GitHub

gem uninstall win32-api gem install win32-api --platform=ruby

Cliff