Thanks for identifying those options. Apple charges a £60 fee for shipping on the returned item, which seems a bit steep! For a few quid more, I might just hop on a plane and return it to the store in person. Based on your reactions to my 18 GB used-up HD space already, I did some looking: Applications: 4 GB Library: 4 GB System: 1 GB Users: 1 GB It's still only around 10 GB. Makes me wonder if the computer is faulty. . .