if (document.images) {

            image1on = new Image();
            image1on.src = "imagenes/descripcion_i.gif";
            image2on = new Image();
            image2on.src = "imagenes/aplicaciones_i.gif";
            image3on = new Image();
            image3on.src = "imagenes/ventajas_i.gif";
            image4on = new Image();
            image4on.src = "imagenes/conexion_i.gif";
            image5on = new Image();
            image5on.src = "imagenes/velocidades_i.gif";
            image6on = new Image();
            image6on.src = "imagenes/preguntas_i.gif";
            image7on = new Image();
            image7on.src = "imagenes/form_i.gif";
	
            image1off = new Image();
            image1off.src = "imagenes/descripcion_n.gif";
            image2off = new Image();
            image2off.src = "imagenes/aplicaciones_n.gif";
            image3off = new Image();
            image3off.src = "imagenes/ventajas_n.gif";
            image4off = new Image();
            image4off.src = "imagenes/conexion_n.gif";
            image5off = new Image();
            image5off.src = "imagenes/velocidades_n.gif";
            image6off = new Image();
            image6off.src = "imagenes/preguntas_n.gif";
            image7off = new Image();
            image7off.src = "imagenes/form_n.gif";
     
            image1other = new Image();
            image1other.src = "imagenes/descripcion_x.gif";
            image2other = new Image();
            image2other.src = "imagenes/aplicaciones_x.gif";
            image3other = new Image();
            image3other.src = "imagenes/ventajas_x.gif";
            image4other = new Image();
            image4other.src = "imagenes/conexion_x.gif";
            image5other = new Image();
            image5other.src = "imagenes/velocidades_x.gif";
            image6other = new Image();
            image6other.src = "imagenes/primero_x.gif";
            image7other = new Image();
            image7other.src = "imagenes/primero_x.gif";

}


function imgOn(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "on.src");
            document["blanco"].src = eval(imgName + "other.src");
}
}


function imgOff(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "off.src");
            document["blanco"].src = "imagenes/primero_x.gif";
}
}