homeOver=new Image(); homeOver.src="img/nav-home-over.gif";
aboutOver=new Image(); aboutOver.src="img/nav-about-over.gif";
toursOver=new Image(); toursOver.src="img/nav-tours-over.gif";
agriculturalOver=new Image(); agriculturalOver.src="img/nav-agricultural-over.gif";
contactOver=new Image(); contactOver.src="img/nav-contact-over.gif";

oldImage=new Image();

function navOver(object) {
 oldImage.src=document.getElementById(object).src;
 document.getElementById(object).src=eval(object+'Over.src');
}

function navOut(object) {
 document.getElementById(object).src=oldImage.src;
}