var theImages = new Array();
 
theImages[0] = 'images/headers/boat1.jpg'
theImages[1] = 'images/headers/boat2.jpg'
theImages[2] = 'images/headers/ducks.jpg'
theImages[3] = 'images/headers/hills.jpg'
theImages[4] = 'images/headers/rocks.jpg'
theImages[5] = 'images/headers/woods.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="Header Image" />');
}