var how_many_ads = 3;
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;
if (ad==1) {
alt="Interstate Glass, Inc.";
banner="images/header3-mach1.jpg";
width="318";
height="121";
}
if (ad==2) {
alt="Interstate Glass, Inc.";
banner="images/header3-mini.jpg";
width="318";
height="121";
}
if (ad==3) {
alt="Interstate Glass, Inc.";
banner="images/header3-is300.jpg";
width="318";
height="121";
}
document.write('<img src=\"' + banner + '\" width=');
document.write(width + ' height=' + height + ' ');
document.write('alt=\"' + alt + '\" border=0>');