// preloadimages 

	indexon =  new Image();

	indexon.src = "images/usbbhomeon.gif";

	indexoff = new Image();

	indexoff.src = "images/usbbhomeoff.gif";			

	bookson = new Image();

	bookson.src = "images/usbbbookson.gif";						

	booksoff = new Image();

	booksoff.src = "images/usbbbooksoff.gif";

	shortstorieson = new Image();

	shortstorieson.src = "images/usbbshortstorieson.gif";	

	shortstoriesoff = new Image();

	shortstoriesoff.src = "images/usbbshortstoriesoff.gif";	

	aboutisabelon = new Image();

	aboutisabelon.src = "images/usbbaboutisabelon.gif";	

	aboutisabeloff = new Image();

	aboutisabeloff.src = "images/usbbaboutisabeloff.gif";
	
	homeon = new Image();

	homeon.src = "images/usbbtoplefton.gif";	

	homeoff = new Image();

	homeoff.src = "images/usbbtopleftoff.gif";
	

// function to do rollovers on images

	function swapImage(num){

		if (num=="1") document.images ['index'].src = indexon.src;

		else if (num=="2") document.images ['index'].src = indexoff.src;				

		else if (num=="3") document.images ['books'].src = bookson.src;	

		else if (num=="4") document.images ['books'].src = booksoff.src;				

		else if (num=="5") document.images ['shortstories'].src = shortstorieson.src;	

		else if (num=="6") document.images ['shortstories'].src = shortstoriesoff.src;		

		else if (num=="7") document.images ['aboutisabel'].src = aboutisabelon.src;

		else if (num=="8") document.images ['aboutisabel'].src = aboutisabeloff.src;
		
		else if (num=="9") document.images ['home2'].src = homeon.src;

		else if (num=="10") document.images ['home2'].src = homeoff.src;								

		}