var theImages = new Array() 

theImages[0] = 'images/main_image_1.jpg"'
theImages[1] = 'images/main_image_2.jpg"'
theImages[2] = 'images/main_image_3.jpg"'
theImages[3] = 'images/main_image_4.jpg"'
theImages[4] = 'images/main_image_5.jpg"'
theImages[5] = 'images/main_image_6.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]+'" alt="The Art of David Smith" />');
}