function image() {
};

image = new image();
number = 0;

image[number++] = "<img src='images2/Banrural-Virtual-03.gif' border='0'>"
image[number++] = "<img src='images2/Credito-Amigo-02.gif' border='0'>"
image[number++] = "<img src='images2/Seņora-Cuenta-02.gif' border='0'>"
image[number++] = "<img src='images2/bancamigo.gif' border='0'>"
image[number++] = "<img src='images2/cuadernos_con_corazon_vertical.gif' border='0'>"

increment = Math.floor(Math.random() * number);

document.write(image[increment]);