Q:

Failed to build gem native extension when Installing capybara-webkit (0.12.1)

I can't install the Capybara Webkit Driver as I receive this error: 
Installing capybara-webkit (0.12.1) with native extensions
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension. 

        c:/RailsInstaller/Ruby1.9.3/bin/ruby.exe extconf.rb 

I'm running on Windows 7 x64 and as you can see, installed with the RailsInstaller for Windows.  I tried gem install capybara-webkit and right now I have it in my gem file but both return the same error. 
Anyone know how to solve this issue? 

A:

You also need to install QT 4.7.x OpenSource edition (with support for
  mingw32) AND add Qt's bin directory to path. 

This is from official wiki in windows section.  So you probably need to install damn thing.  Can't provide anything more detailed since I'm not using windows for RoR(and suggesting you the same).