if (document.images) {

var button1_up = new Image();
button1_up.src = "hamann_small.jpg";

var button1_over = new Image();
button1_over.src = "hamann_small.gif";
}

function over_button(){
if (document.images) {document["buttonOne"].src=button1_over.src}}

function up_button(){
if (document.images) {document["buttonOne"].src=button1_up.src}}