if (document.images) {
	img_preload = new Array();
	
	var img_url = ["images/button_approach_over.gif", "images/button_contact_over.gif", "images/button_designbackground_over.gif", "images/button_portfolio_over.gif"];
	
	for (var i in img_url) {
		img_preload[i] = new Image();
		img_preload[i].src = img_url[i];
	}
}