Why can't I require express in node.js

I'm trying to get the simplest node.js script to work. Here is the javascript file:

server.js

require("express");

I launch the script using the regulare node command:

$ node server.js

But I get an error:

node.js:201
        throw e; // process.nextTick error, or 'error' event on first tick
              ^
Error: require.paths is removed. Use node_modules folders, or the NODE_PATH environment variable instead.
    at Function.<anonymous> (module.js:378:11)
    at Object.<anonymous> (/home/shawn/.node_libraries/express@2.5.9/index.js:4:21)
    at Module._compile (module.js:441:26)
    at Object..js (module.js:459:10)
    at Module.load (module.js:348:32)
    at Function._load (module.js:308:12)
    at Module.require (module.js:354:17)
    at require (module.js:370:17)
    at Object.<anonymous> (/home/shawn/Documents/Projets/passingData/server.js:3:15)
    at Module._compile (module.js:441:26)

What's going on?

UPDATE

Interestingly enough, using npm install express outputs a similar result:

node.js:201
        throw e; // process.nextTick error, or 'error' event on first tick
              ^
Error: require.paths is removed. Use node_modules folders, or the NODE_PATH environment variable instead.
    at Function.<anonymous> (module.js:378:11)
    at Object.<anonymous> (/home/shawn/.node_libraries/mkdirp@0.3.0/index.js:4:21)
    at Module._compile (module.js:441:26)
    at Object..js (module.js:459:10)
    at Module.load (module.js:348:32)
    at Function._load (module.js:308:12)
    at Module.require (module.js:354:17)
    at require (module.js:370:17)
    at Object.<anonymous> (/usr/lib/nodejs/fstream/lib/dir-reader.js:11:13)
    at Module._compile (module.js:441:26)