function secondary_image_rollover() {
	var img = this.getChildren('img')[0].src;
	$$('.photos .primary')[0].setStyle('background-image', 'url('+img+')');
}

function reset_primary_image() {
	var node = $$('.photos .primary')[0];
	var img = node.getChildren('img')[0].src;
	node.setStyle('background-image', 'url('+img+')');
}

window.addEvent('domready', function() {
	$$('.photos .secondary').addEvent('mouseover', secondary_image_rollover);
	$$('.photos .secondary').addEvent('mouseout', reset_primary_image);
});