$(document).ready(function(){
	$(".topNav").hover(
		function(event){
			if (this.id){
				document.getElementById(this.id + "Img").src = "/~tshto/img/" + this.id + "_on.jpg";
			}
		}, 
		function(event){
			if(this.id){
				document.getElementById(this.id + "Img").src = "/~tshto/img/" + this.id + "_off.jpg";
			}
		}
	);
});