overImgClassName = 'rollover';
overImgPostfix = '_f2';
Event.observe(window, 'load', RN_setMouseOverImages, false);
function RN_setMouseOverImages() {
	var btns = $A(document.getElementsByClassName(overImgClassName));
	btns.each(
		function (node){
			node.imgsrc = node.src;
			node.imgsrc_over = node.src.replace('.gif', overImgPostfix+'.gif').replace('.jpg', overImgPostfix+'.jpg');
			node.onmouseover = function() { this.src = this.imgsrc_over; };
			node.onmouseout = function() { this.src = this.imgsrc; };
		}
	);
}