images = new Array(5);

images[0] = "<img src='images/hole_punch_2.jpg' alt='hole punch courtesy of freephotosbank.com'>";

images[1] = "<img src='images/pens_2.jpg' alt='pens'>";

images[2] = "<img src='images/folders_2.jpg' alt='folders'>";

images[3] = "<img src='images/office_chairs_2.jpg' alt='office chairs'>";

images[4] = "<img src='images/envelopes_2.jpg' alt='envelopes'>";

index = Math.floor(Math.random() * images.length);

document.write(images[index]);