var nav = navigator
browserIE = ((nav.appName == "Microsoft Internet Explorer") && (parseInt(nav.appVersion) >= 4 ))
browserNS1 = ((nav.appName == "Netscape") && (parseInt(nav.appVersion) < 5 ) ) // Netscape < 4.7
browserNS2 = ((nav.appName == "Netscape") && (parseInt(nav.appVersion) >= 5 ) )// Netscape >= 6

// Precarga de imágenes ----------------------------------------
var i;
var imagenes = new Array("images/menu/consultoria.jpg","images/menu/consultoriaBis.jpg","images/menu/mantenimiento.jpg","images/menu/mantenimientoBis.jpg","images/menu/ventaEquipos.jpg","images/menu/ventaEquiposBis.jpg","images/logo_Argos.png","images/logo_Argos_Bis.png","images/logo_Dipro.png","images/logo_Dipro_Bis.png","images/logo_Vtiger.png","images/logo_Vtiger_Bis.png","images/logo_Derveny.png","images/logo_Derveny_Bis.png","images/logo_Espacyo.png","images/logo_Espacyo_Bis.png","images/logo_Talleres.png","images/logo_Talleres_Bis.png","images/menu/dweb.jpg","images/menu/dweb_Bis.jpg","images/menu/servWeb.jpg","images/menu/servWeb_Bis.jpg");
var lista_imagenes = new Array();
function cargarimagenes(){
for(i in imagenes){
lista_imagenes[i] = new Image();
lista_imagenes[i].src = imagenes[i];
}
}

function cambio(nombre,index){
                if ((browserIE)||(browserNS2)){

                        document.images[nombre].src = lista_imagenes[parseInt(index)].src;

                }
                else if (browserNS1){

                        document.layers["upc3"].document.images[nombre].src = lista_imagenes[parseInt(index)].src;
                }
}