These “Super-Efficient Image Rollovers” are not Efficient at all. They use an image of all five buttons for each state. When they should be using an image of just one blank button. With text over top of it. Like this:

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By using text, the image for each state is 1/5 of the size. Forget all that image-map crap too. I hate all that bloated code.
-PlattDaddy