var randnum = Math.random();
var inum = 7;
var rand1 = Math.round(randnum * (inum-1)) + 1;
images = new Array
images[1] = "bg_01.jpg"
images[2] = "bg_02.jpg"
images[3] = "bg_01.jpg"
images[4] = "bg_04.jpg"
images[5] = "bg_05.jpg"
images[6] = "bg_06.jpg"
images[7] = "bg_07.jpg"
var image = images[rand1]