Selecting Desired Part of Image With Mouse

Hi everyone

i want to select some part of image which is on picturebox with mouse.
i will click the mouse down on the image, and then i will make a rectangle with mouse (like on the wallpaper image). when i stop, clicking mouse button, the small image in the rectangle should be copied to another picturebox.

thanks for your helping
Example:
http://img15.imageshack.us/img15/4764/mousegx1.jpg