var width = "644"
var height = "150"
var border = "0"

var imagenumber = 3 ;
var randomnumber = Math.random() ;
var rand1 = Math.round( (imagenumber-1) * randomnumber) + 1 ;
images = new Array
images[1] = "images/pic_01.jpg"
//images[2] = "images/pic_02.jpg"
images[2] = "images/pic_03.jpg"
images[3] = "images/pic_04.jpg"
var image = images[rand1]

var ad = ""
ad += '<img src="' + image + '" width=' + width
ad += '\n height=' + height + ' border=' + border