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; };

		}

	);

}