var bannerFn = "nextBannerImage()";
var bannerImages = new Array(
  'apache.gif',
  'centos.gif',
  'fmp.gif',
  'mysql.gif',
  'osx.gif',
  'pgsql.gif',
  'php.gif',
  'rhel4.gif',
  'windows.gif'
);

function getInterval() {
  return (1000 + parseInt( Math.random()*4000.0) );
}
  
function pickImage() {
  imageNumber = parseInt( Math.random()*bannerImages.length );
  return( '/graphics/banner/' + bannerImages[imageNumber] );
}
  
function nextBannerImage() {
  bannerEl.src = ( pickImage() );
  bannerWait = getInterval();
  setTimeout( bannerFn, bannerWait );
}