This installed node 0.2.6 on my machine.

theres a node manager in the npm repository called n.

npm intsall n

n install 0.4.0

want to use an older version installed?

n use 0.2.6

Nave plays well with npm, so you can have different sets of libraries for the different versions of node that you have installed (similar to rvm if you're a rubyist.) This is mostly important when you have libraries that are compiled C/C++.