function swap(imageName,url) {
  var objImage = document.getElementById(imageName);
  objImage.src = url;
}

var lendersLogos = new Array();
    lendersLogos[0]  = new Image(257,80);
    lendersLogos[1]  = new Image(257,80);
    lendersLogos[2]  = new Image(257,80);
    lendersLogos[3]  = new Image(257,80);
    lendersLogos[4]  = new Image(257,80);
    lendersLogos[5]  = new Image(257,80);
    lendersLogos[6]  = new Image(257,80);
    lendersLogos[7]  = new Image(257,80);
    lendersLogos[8]  = new Image(257,80);
    lendersLogos[9]  = new Image(257,80);
    lendersLogos[10] = new Image(257,80);
    lendersLogos[11] = new Image(257,80);

    lendersLogos[0].src  = 'images/logos/logo_anz.jpg';
    lendersLogos[1].src  = 'images/logos/logo_bankwest.jpg';
    lendersLogos[2].src  = 'images/logos/logo_citibank.jpg';
    lendersLogos[3].src  = 'images/logos/logo_com.jpg';
    lendersLogos[4].src  = 'images/logos/logo_ing.jpg';
    lendersLogos[5].src  = 'images/logos/logo_macquarie.jpg';
    lendersLogos[6].src  = 'images/logos/logo_nab.jpg';
    lendersLogos[7].src  = 'images/logos/logo_rams.jpg';
    lendersLogos[8].src  = 'images/logos/logo_stgeorge.jpg';
    lendersLogos[9].src  = 'images/logos/logo_suncorp.jpg';
    lendersLogos[10].src = 'images/logos/logo_wpac.jpg';
    lendersLogos[11].src = 'images/logos/logo_violet.jpg';

var numberOfImages = lendersLogos.length;

function autoSwap() {
    var randomImage=Math.floor(Math.random()*numberOfImages)
    swap('lenderlogo',lendersLogos[randomImage].src);
    setTimeout('autoSwap()',(3000));
}