var nav=new Array("philosophy","integration","usability","hvhf","contacts");
var selected="philo"
function down(img_name){

	for(i=0;i<nav.length;i++){
		if(img_name!=nav[i]){
 		 	document[nav[i]].src = "images/nav_"+nav[i]+".gif";
		}else{
			document[img_name].src = "images/nav_over_"+nav[i]+".gif";
			selected=img_name
		}
   }
return false;
}

function over(img_name){
	
			document[img_name].src = "images/nav_over_"+img_name+".gif";
}
function out(img_name){
	if(selected!=img_name){
			document[img_name].src = "images/nav_"+img_name+".gif";
}

}