var how_many_ads = 2;
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;

if (ad==1) {
txt="";
url="http://www.chesstoday.net/";
alt="ChessToday.Net - Click here!";
banner="images/banners/468x60/468x60_00.gif";
width="468";
height="60";
}

if (ad==2) {
txt="";
url="https://www.web-guardian.com/gmsquare/cgi-bin/store/commerce.cgi";
alt="";
banner="images/banners/468x60/468x60_01.gif";
width="468";
height="60";
}

document.write('<center>');
document.write('<a href=\"' + url + '\" target=\"_top\">');
document.write('<img src=\"' + banner + '\" width=')
document.write(width + ' height=' + height + ' ');
document.write('alt=\"' + alt + '\" border=0><br>');
document.write('<small>' + txt + '</small></a>');
document.write('</center>');