var bannerImg = new Array();
  bannerImg[0]="images/main1.jpg";
  bannerImg[1]="images/main2.jpg";
  bannerImg[2]="images/main3.jpg";

var newBanner = 0;
var totalBan = bannerImg.length;

function cycleBan() {
  newBanner++;
  if (newBanner == totalBan) {
    newBanner = 0;
  }
  document.banner.src=bannerImg[newBanner];
  setTimeout("cycleBan()", 6*1000);
}
window.onload=cycleBan;