Javascript image scrolling

Hi Everyone, I need a way to "scroll" through an image. Basically, I have a large image and I want to have a webpage that when loaded displays a portion of the image in a box (div tag / asp.net panel / whatever). When the user clicks a button, I need to the image to start "scrolling/moving" through the box. I have attached two animated gifs. The first, called "[login to view URL]" shows the portion of the image to be displayed as a function of time. The second image "[login to view URL]" shows what the suer would see as they view the webpage. I made these samples in Photoshop, and they are super rough. I need this animation to be very smooth. The pattern that the box moves over the image is basically a "Z" Any questions, feel free to ask! Thanks!