Installing Node.js in Ubuntu in 10 simple Steps

apt-get update
apt-get install build-essential openssl libssl-dev

cd ~/
mkdir builds
cd builds

wget http://nodejs.org/dist/v0.7.1/node-v0.7.1.tar.gz
tar xzvf node-v0.7.1.tar.gz

cd node-v0.7.1

./configure
make && make install

If you need a different version of node.js go to http://nodejs.org/dist/ to see all available versions.