var theImages = new Array()

theImages[0] = 'http://eia-global.org/images/header/Header01a.gif'
theImages[1] = 'http://eia-global.org/images/header/Header01b.gif'
theImages[2] = 'http://eia-global.org/images/header/Header01c.gif'
theImages[3] = 'http://eia-global.org/images/header/Header01d.gif'
theImages[4] = 'http://eia-global.org/images/header/Header01e.gif'

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]+'">');
}