function externalLinks() {
 if (!document.getElementsByTagName) return;
 var anchors = document.getElementsByTagName("a");
 for (var i=0; i<anchors.length; i++) {
   var anchor = anchors[i];
   if (anchor.getAttribute("href") &&
       anchor.getAttribute("rel") == "external")
     anchor.target = "_blank";
 }
}

function changeImage(which,whichImage){
	document.getElementById(which).src=""+whichImage;
}

function changeNav(which){
		document.getElementById(which).className="page_on";  //sets the nav item on
}

//preload nav images
if (document.images){
  pic1= new Image(153,74); 
  pic1.src="images/left_nav_1_on.jpg"; 

  pic2= new Image(153,74); 
  pic2.src="images/left_nav_2_on.jpg"; 

  pic3= new Image(153,74); 
  pic3.src="images/left_nav_3_on.jpg"; 
  
  pic4= new Image(153,74); 
  pic4.src="images/left_nav_4_on.jpg"; 
}