function newImage(arg) {
rslt = new Image();
rslt.src = arg;
return rslt;
}

function bOver(image) {
document[image].src = eval(image +"_over.src");
}

function bOn(image) {
document[image].src = eval(image +"_on.src");
}

function bOut(image) {
document[image].src = eval(image +"_off.src");
}

b0_off = newImage('images/0_up.gif');
b0_over = newImage('images/0_over.gif');
b0_on = newImage('images/0_down.gif');