a {
   display: block;
   background: url(sprite.png) no-repeat;
   height: 64px;
   width: 240px;
}

a:hover {
   background-position: 0 -64px;
}

Using a sprite is a good idea as it lowers the HTTP-Request. Here is a simple example on how to use this technique. Using a sprite, we can create the hover effect by changing the position of the background image down to a certain height to show the background to the button on hover. A simple yet effective technique. The drawback of using multiple sprites on an image is that you cannot repeat it.

Basic css sprite button

CSS