var randnum = Math.random(); 
var inum = 8; 
// Change this number to the number of images you are using. 
var rand1 = Math.round(randnum * (inum-1)) + 1; 
images = new Array;
images[1] = "bnimages/linksphoto1.jpg"; 
images[2] = "bnimages/linksphoto2.jpg";
images[3] = "bnimages/linksphoto4.jpg";
images[4] = "bnimages/linksphoto5.jpg";
images[5] = "bnimages/linksphoto6.jpg";
images[6] = "bnimages/linksphoto7.jpg";
images[7] = "bnimages/linksphoto8.jpg";
images[8] = "bnimages/linksphoto3.jpg";
// Ensure you have an array item for every image you are using. 
var image = images[rand1];