var theImages = new Array() 
theImages[0] = '001.jpg'
theImages[1] = '002.jpg'
theImages[2] = '003.jpg'
theImages[3] = '004.jpg'
theImages[4] = '005.jpg'
theImages[5] = '006.jpg'
theImages[6] = '007.jpg'
theImages[7] = '008.jpg'
theImages[8] = '009.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 id="bgImage" src="../images/bg/'+theImages[whichImage]+'">');
}