DHTML enlarge image

In an HTML page, show an image (original image size of approximatly 500 x 300 pixels) with fixed height and width 100 x 100.? When the user mouses over the page, show the image (with no height or widht specifications so the image shows at original height and width) in an IFRAME positioned to show on the page (as best as possible).? When the user mouses off of the IFRAME it disappears showing the original page and small image.