var imagenumber = 6 ;
var randomnumber = Math.random() ;
var rand1 = Math.round( (imagenumber-1) * randomnumber) + 1 ;
images = new Array
images[1] = "img/topImg_01.gif"
images[2] = "img/topImg_02.gif"
images[3] = "img/topImg_03.gif"
images[4] = "img/topImg_04.gif"
images[5] = "img/topImg_05.gif"
images[6] = "img/topImg_06.gif"
var image = images[rand1]