var Banner = {
  count: 5,
  seconds: 10,
  pattern: /(.*\/images\/header\/)(\d)(\.jpg.*)/
}


Banner.init = function() {
  Banner.div = $('banner')
  var bg_str = Banner.div.style.background.match(Banner.pattern)
  Banner.bg_left = bg_str[1]
  Banner.bg_right = bg_str[3]
  Banner.current = parseInt(bg_str[2])
  Banner.queueNextSlide()
}

Banner.queueNextSlide = function() {
  setTimeout(Banner.showNextSlide, Banner.seconds * 1000)
}

Banner.showNextSlide = function() {
  Banner.current += 1
  if (Banner.current > Banner.count) { Banner.current = 1 }
  Banner.div.style.background = Banner.bg_left + Banner.current + Banner.bg_right
  Banner.queueNextSlide()
}

Event.observe(window, 'load', Banner.init)