image = new Array

image[1]="random/01.jpg"
image[2]="random/02.jpg"
image[3]="random/03.jpg"
image[4]="random/04.jpg"	

random_num = (Math.round((Math.random()*3)+1))

document.write("<img width=\"700\" height=\"120\" src=\"" + image[random_num] + "\">");