a= new Image(); a.src="images/nav_home.gif";
	b= new Image(); b.src="images/nav_about.gif";
	c= new Image(); c.src="images/nav_nav_explore.gif";
	d= new Image(); d.src="images/nav_rates.gif";
	e= new Image(); e.src="images/nav_conference.gif";
	
	
	
	function rollThis(whichPic, whichImage){
		document.images[whichPic].src = whichImage;
	}
	
	function changeBack(whichPic){
		document.images[whichPic].src="cplogo.jpg";
	}
	
	function rollem(whichSlot,whatImage){
	document.images[whichSlot].src = whatImage;
	}
	function backUp(whichSlot,whatImage){
	document.images[whichSlot].src = whatImage;
	}