Animal Farm - known to us all from school. Fun, but obvious.
Nineteen Eighty-Four - a fantastic science fiction book about a dystopian future, written at a time when the phrase "dystopian future" wasn't such an ugly cliché. Gave wonderful and permanent images to feed the politically cynical, such as Big Brother, thought police, doublespeak and
Go read it now. Do yourself a favour.
Orwell in Tribune - a collection of his columns and articles for the now-defunct Tribune magazine. He wrote mainly about socialism and language, and his articles are always interesting.