Please, forget about your 64 (OMG!) pictureboxes and draw the board yourself.
Check out
this[
^] excellent
CodeProject article for details on drawing the board and for the chess game implementation at all!
[UPDATE - After the comment from OP]
Well, it didn't changed anything for me. Personally I'd draw the board myself, because the
PictureBox
control is very very inefficient! But, if you want to go with it OK.
So you could set the image of a given picturebox by using its
Image
property:
pictureBox1.Image = pictureBox2.Image;
pictureBox2.Image = null;
I must tell you that personally I would NEVER do things like this and that's way I've provided a link to an excellent article which contains chess game logic and board drawing implementation in C#.
[/UPDATE]