Take a square and cut it as you wish into a finite number of pieces. Rearrange the pieces without rotating or flipping any of them to form an new square that is rotated 45-degrees compared to the
original.
Here is one possible solution. I'm not sure how to post a graphic so instead a link (to a geocities page, sorry about the pop-ups)
http://www.geocities.com/s_hart/squares.html