$(document).ready(function(){
	//keep original source to place back on mouseout
	var originalSrc = $('#sfeer img').attr('src');

	$('#navigation ul li').hover(
		function(){
			if (this.id != '') {
				$('#sfeer img').attr('src', '/images/sfeer_' + this.id + '.jpg'); //mouseover
			}
		},
		function(){
			$('#sfeer img').attr('src', originalSrc); // mouseout
		}
	);

});