Can't say Hello World in node

I am trying to follow the following the tutorial The Node Beginner Book

I have installed node and mongodb successfully, when i do node -v it gives me v0.5.11-pre but when i save the file say hello.js in Home/node/ and write node hello.js in the terminal it gives me the following error

ubuntu@ubuntu:~/Downloads$ node hello.js

node.js:201
        throw e; // process.nextTick error, or 'error' event on first tick
              ^ Error: Cannot find module '/home/ubuntu/Downloads/hello.js'
    at Function._resolveFilename (module.js:334:11)
    at Function._load (module.js:279:25)
    at Array.0 (module.js:470:10)
    at EventEmitter._tickCallback (node.js:192:40)

Please help me find what I am doing wrong here. I'm using Ubuntu in a virtual machine.