If you want a machine that doesn't take up much space, have you considered an iMac?
I got myself one from the Apple refurb store over a year ago, saved about £200 over the price of a regular one and you would never know it wasn't new (From what I've read most of the time they go back for component failures when they've been powered up out of the box - dodgy drives, faulty memory - so when you get it it's like getting a new machine).
Even if you haven't used a Mac before it won't take you long to get used to it, and you can run Windows on it if you really needed to (as well as Linux, Open Solaris etc...)