var how_many_ads = 4;
var now = new Date();
var sec = now.getSeconds();
var ad = sec % how_many_ads;
var width="212";
var height="152";
ad +=1;

if (ad==1) {
banner="http://www.discoveryvip.com/images/Learning_template/message4.gif";
alt="Discoveryvip Computer Training";
url="http://www.discoveryvip.com/Courseware/Business_Management.htm";
}

if (ad==2) {
banner="http://www.discoveryvip.com/images/Learning_template/message5.gif";
alt="Discoveryvip Computer Training"
url="http://www.discoveryvip.com";
}

if (ad==3) {
banner="http://www.discoveryvip.com/images/Learning_template/message6.gif";
alt="Discoveryvip Computer Training"
url="http://www.discoveryvip.com";
}

if (ad==4) {
banner="http://www.discoveryvip.com/images/Learning_template/message7.gif";
alt="Discoveryvip Computer Training"
url="http://www.discoveryvip.com";
}

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>');