if (document.images) {

	abouton = new Image();
	abouton.src = '/images/f_about_on.gif';
	aboutoff = new Image();
	aboutoff.src = '/images/f_about.gif';
	
	serviceson = new Image();
	serviceson.src = '/images/f_services_on.gif';
	servicesoff = new Image();
	servicesoff.src = '/images/f_services.gif';
	
	productson = new Image();
	productson.src = '/images/f_products_on.gif';
	productsoff = new Image();
	productsoff.src = '/images/f_products.gif';
	
	contacton = new Image();
	contacton.src = '/images/f_contact_on.gif';
	contactoff = new Image();
	contactoff.src = '/images/f_contact.gif';
	
}

function turnOn(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "on.src");
  }
}

function turnOff(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "off.src");
  }
}