//------------------------------------------------------------------------------Random
//------------------------random gif
function image() {
};

image = new image();
number = 0;

// imageArray
image[number++] = "<img src='images/banner1.jpg' width='540' height='150'>"
image[number++] = "<img src='images/banner2.jpg' width='540' height='150'>"
image[number++] = "<img src='images/banner3.jpg' width='540' height='150'>"
image[number++] = "<img src='images/banner4.jpg' width='540' height='150'>"
image[number++] = "<img src='images/banner5.jpg' width='540' height='150'>"

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

document.write(image[increment]);
//--------