var theImages = new Array() 

theImages[0] = '/images/purple/upperhead01.jpg'
theImages[1] = '/images/purple/upperhead02.jpg'
theImages[2] = '/images/purple/upperhead03.jpg'
theImages[3] = '/images/purple/upperhead04.jpg'
theImages[4] = '/images/purple/upperhead05.jpg'
theImages[5] = '/images/purple/upperhead06.jpg'

var j = 0
var p = theImages.length;
var preBuffer = new Array()
for (i = 0; i < p; i++){
preBuffer[i] = new Image()
preBuffer[i].src = theImages[i]
}
var whichImage = Math.round(Math.random()*(p-1));
function showImage(){
document.write('<img src="'+theImages[whichImage]+'" width="584" height="87" border="0" alt="random campus banner image">');
}

showImage();