$(function($){	
	$.preload( '#cntHead img', {
	    	find:'.jpg',
	    	replace:'-ON.jpg'
	});
	/*		or
	$('#rollover-images img').preload({
		find:'.jpg',
	    replace:'-on.jpg'
	});
	*/
	//add animation
	$('#cntHead img').hover(function(){
		if (this.className == 'rollover') {
			this.src = this.src.replace('.jpg','-ON.jpg');	
		}
	},function(){
		if (this.className == 'rollover') {
			this.src = this.src.replace('-ON','');
		}
	});
});