if (document.images)
{
	var home_off = new Image();  
	home_off.src = "../images/home.gif";
  	var home_on = new Image();  
	home_on.src = "../images/home_over.gif";
	var certificates_off = new Image();  
	certificates_off.src = "../images/certificates.gif";
  	var certificates_on = new Image();  
	certificates_on.src = "../images/certificates_over.gif";
	var products_off = new Image();  
	products_off.src = "../images/products.gif";
  	var products_on = new Image();  
	products_on.src = "../images/products_over.gif";
	var contact_off = new Image();  
	contact_off.src = "../images/contact.gif";
  	var contact_on = new Image();  
	contact_on.src = "../images/contact_over.gif";
}

function act(imgName) {
	if (document.images)  
	{
	    document[imgName].src = eval(imgName + "_on.src");
	}
}

function inact(imgName) {
	if (document.images)  
	{
	    document[imgName].src = eval(imgName + "_off.src");
	}
}