you can use control and the arrow keys, or you can also use control with the number keys (1 or space 1, 2 for space 2, etc.).
EDIT: wow, too slow today! to make up, i'll provide visual aids. 🙂
EDIT #2: if you want to move from space 2 to space 3, you don't have to press ctrl-down and then ctr-left. you can just press ctr-right, sending you to the next numbered space. pressing ctr-right from space 4 would move you back to space 1.