function random_imglink(){
  var img=new Array()
  img[1]="images/banner/mainbanner1.jpg"
  img[2]="images/banner/mainbanner2.jpg"
  img[3]="images/banner/mainbanner3.jpg"
  img[4]="images/banner/mainbanner4.jpg"
  img[5]="images/banner/mainbanner5.jpg"
  img[6]="images/banner/mainbanner6.jpg"

  var ry=Math.floor(Math.random()*img.length)

  if (ry==0)
     ry=1
     document.write('<img src="'+img[ry]+'" border="0" />')
}

  random_imglink()