yes, much better way through
yes, much better way through css. one image for all states of rollover. The for the :hover state of the rollover, just change image position to reveal the other part of the graphic. study my code to see what I mean.
the home page uses this technique for the navigation, and the 1 2 3 4 5. Its very easy to achieve, and tons of fun! Remember, each state (off, hover, click, whatever) can be one graphic! You may have to save the page to retrieve all the graphics.