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

if (ad==1)
{
//728x90
var rnd = (new String(Math.random())).substring(2,8) + (((new Date()).getTime()) & 262143);
document.write('<scri' + 'pt language="JavaScript1.1" type="text/javascript" src="http://ads.us.e-planning.net/eb/3/13e1/9a7e90affb7a1daa?o=j&rnd=' + rnd + '"></scr' + 'ipt>');
}

if (ad==2)
{
//160x600
var rnd = (new String(Math.random())).substring(2,8) + (((new Date()).getTime()) & 262143);
document.write('<scri' + 'pt language="JavaScript1.1" type="text/javascript" src="http://ads.us.e-planning.net/eb/3/13e1/0d216969fa3bb918?o=j&rnd=' + rnd + '"></scr' + 'ipt>');
}