var theImages = new Array() 

        theImages[0] = 'images/ih_01.jpg'
        theImages[1] = 'images/ih_02.jpg'
        theImages[2] = 'images/ih_03.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]+'">');
        }