$(ConfigureRollovers);

function ConfigureRollovers() {

  $(".rollover").hover(
        function(){
                if($(this).attr("src").indexOf("-off") != -1) {
                        var newSrc = $(this).attr("src").replace("-off","-on");
                        $(this).attr("src",newSrc);
                }
        },
        function(){
                if($(this).attr("src").indexOf("-on") != -1) {
                        var oldSrc = $(this).attr("src").replace("-on","-off");
                        $(this).attr("src",oldSrc);
                }
        }
  );

  // Prefetch!
  $(".rollover").each(function(key, elm) {
    $("").attr( "src", $(this).attr("src").replace("-off", "-on"));
  });
}