Don't listen to these fags, OP. Ubuntu is a great OS and easier to install than windows, though you're going to have to learn a bit of networking and maybe some UNIX if you want to get the most bang for your buck out of your server setup. This is actually much easier than it sounds.

There's an introduction to the command line here:

https://help.ubuntu.com/community/UsingTheTerminal

And a guide to setting up a server here:

http://doc.ubuntu.com/ubuntu/serverguide/C/

As to the hard drive, what do you need to know? Are you having trouble physically connecting it?