isNS4 = (document.layers) ? 1 : 0;
	
function rollOver(item, over) {    
 
	if (!document.images) {return};
	
	if (isNS4 == 1){
		theElement = document.images[item];
	} else {
		theElement = document.all[item];
	}
	
   	if (over) { 		
		theElement.src = "images/" + item + "-on.jpg"
	} else { 
		theElement.src = "images/" + item + "-off.jpg"
	};
}