Strong client side data validation.
There are several buttons with images as the background.
When you mouseover the image is changed to a highlighted image.
When you mouseout you are back to the original image.
If you click on a button? the image should display the highlighted version and not change if you mouse out or over.
And if any other button had been pressed it should revert back to its original state.
When any of these buttons are clicked a request is sent to the server.
Server will send back static html or xml or maybe some script.. haven't work out this part yet.
What ever is sent back is displayed in a div on the web page.