I\'m trying to install bcrypt-ruby on Windows Vista.
So far, I have been able to install nmake.exe from a MS knowledge base article and cl.exe from installing Visual
For me, a part of the problem was in the fact that I had Ruby2.0.0 x64 installed (I'm running win8), which seemed to be incompatible with the gcc compiler I was using.
I've removed my ruby installation, and installed ruby 1.9.3 together with Bundler, Rails and some other packages with the use railsInstaller (http://railsinstaller.org/) and I'm now able to install bcrypt-ruby :)