As I run this piece of code using
var sys = require('sys'); sys.puts('Hello, World');
I'm getting the following as an error
axconfig: port 1 not active
axconfig: port 2 not active
Warning: This is old but it might still work.
You didn't install node.js but the package node (that contains some other unrelated software) for your linux distro.
You can install node.js three ways: Using git, downloading the version file, or installing through the package manager, I recommend using the package manager for ease-of-use and the ability to easily update.
Check out Installing Node.js via Package Manager. It has instructions on how to install using the package manager of your preference.
Go the the downloads page of node.js and download the package for your OS. Don't forget that, doing i this way, doesn't auto-update node.js later on!
Source Compilation / git
First you need git and a compiler, here is how you install them on debian/ubuntu (this depends on your package manager):
sudo apt-get install git-core build-essential
(If you don't want to use git, you can download the source code from the website. You still need build-essential or equivalent for your OS.)
Then go to a folder where the "node" repository will be placed, something like
~/src is good enough, and do this:
git clone https://github.com/joyent/node.git
Then enter the node directory, configure it and build it.
cd node && ./configure && make
Everything should go well. Before installing node you can optionally run the tests to check for any problems:
...and we are done.
You can test those lines of code using node-repl (node's REPL, think "interactive interpreter"), just type
node-repl, quit with Ctrl+D.