//sfHover = function() {
//	var sfEls = document.getElementById("nav_fmt").getElementsByTagName("LI");
//	for (var i=0; i<sfEls.length; i++) {
//		sfEls[i].onmouseover=function() {
//			this.className+=" sfhover";
//		}
//		sfEls[i].onmouseout=function() {
//			this.className=this.className.replace(new RegExp(" sfhover\\b"), "");
//		}
//	}
//}
//if (window.attachEvent) window.attachEvent("onload", sfHover);

/* this function preloads the navigation images */
if (document.images)
  
  { 
   topnav1on = new Image();
	topnav1on.src = "../images/nav_home_on.gif";
	topnav1off = new Image();
	topnav1off.src = "../images/nav_home.gif";
	
	topnav2on = new Image();
	topnav2on.src = "../images/nav_health_on.gif";
	topnav2off = new Image();
	topnav2off.src = "../images/nav_health.gif";
	
	topnav3on = new Image();
	topnav3on.src = "../images/nav_drugs_treatments_on.gif";
	topnav3off = new Image();
	topnav3off.src = "../images/nav_drugs_treatments.gif";
	
	topnav4on = new Image();
	topnav4on.src = "../images/nav_womens_health_on.gif";
	topnav4off = new Image();
	topnav4off.src = "../images/nav_womens_health.gif";
	
	topnav5on = new Image();
	topnav5on.src = "../images/nav_mens_health_on.gif";
	topnav5off = new Image();
	topnav5off.src = "../images/nav_mens_health.gif";
	
	topnav6on = new Image();
	topnav6on.src = "../images/nav_childrens_health_on.gif";
	topnav6off = new Image();
	topnav6off.src = "../images/nav_childrens_health.gif";
	
	topnav7on = new Image();
	topnav7on.src = "../images/nav_health_news_on.gif";
	topnav7off = new Image();
	topnav7off.src = "../images/nav_health_news.gif";
}

  
<!-- the next 2 functions are for the image rollovers -->
var selected = "x";

function imgAct(imgName) {
	if (document.images) {
		document[imgName].src = eval(imgName + "on.src");
	}
}
function imgInact(imgName) {
	if (document.images) {
         if (imgName != selected)
	{
		document[imgName].src = eval(imgName + "off.src");
		
	}
	}
}