var imagenumber = 4 ; 
var randomnumber = Math.random() ; 
var rand1 = Math.round( (imagenumber-1) * randomnumber) + 1 ; 
images = new Array 
images[1] = "images/pic_s_m0007.jpg" 
images[2] = "images/pic_s_m0004.jpg" 
images[3] = "images/pic_s_m0005.jpg"
images[4] = "images/pic_s_m0003.jpg"
var image = images[rand1]