var how_many_ads = 1;

                            var now = new Date();

                            var sec = now.getSeconds();

                            var ad = sec % how_many_ads;

                            ad +=1;
if (ad==1) 
{

                                            url="http://www.wwf.org.uk";

                                            alt="wwf";

                                            banner="images/banner/1150032267ban.gif";

                                            width="468";

                                            height="60";

                                            }




                    document.write('<center>');

                    document.write('<a href="' + url + '" target="_blank">');

                    document.write('<img src="/' + banner + '" width=')

                    document.write(width + ' height=' + height + ' ');

                    document.write('alt="' + alt + '" border=0><br>');

                    document.write('</a>');

                    document.write('</center>');