Node.js cannot find installed module on Windows

I am learning Node.js at the moment on Windows. Several modules are installed globally with npm.cmd, and Node.js failed to find the installed modules. Take Jade, for example,

npm install jade -g

Jade is installed in directory "C:\Program Files (x86)\nodejs\node_modules", but the following code will fail with a "Cannot find module 'jade'" error,

var jade = require('jade');

However, the code will run successfully when Jade is locally installed (without the -g option in npm). I don't want to use locally-installed modules; it's a waste of disk space for me. How can I make the globally-installed modules work on Windows?