Can somebody please help me with this brain teaser/puzzle?

Question

There are nine squares that make up a big square. There are 2 black knights in the top 2 corners and 2 white knights in the bottom two squares. Using only chess moves, get the 4 knights to switch places in only 7 moves.

If i wasn't clear, here's a link.

http://www.areyougame.com/interact/item.asp?itemno=30202&sa=18

Answer 1

Yes, I can help.