var randomnumber;
		var x;
		var books;
		
		books = 4;
		
		randomnumber = Math.floor(Math.random() * books);
		randomnumber = randomnumber + 1;
		
		switch(randomnumber)
			{
			case 1:
				document.write('<iframe src="http://www.trifind.net/b/BBSC/2009/ban/1.html" width=468 height=60 frameborder=0 scrolling=no marginwidth=0 marginheight=0></iframe>');
				break;
			case 2:
				document.write('<iframe src="http://www.trifind.net/b/BBSC/2009/ban/2.html" width=468 height=60 frameborder=0 scrolling=no marginwidth=0 marginheight=0></iframe>');
				break;
			case 3:
				document.write('<iframe src="http://www.trifind.net/b/BBSC/2009/ban/3.html" width=468 height=60 frameborder=0 scrolling=no marginwidth=0 marginheight=0></iframe>');
				break;
			case 4:
				document.write('<a href="http://www.4peaksracing.com/" target="_blank"><img src="http://www.findaraceevent.com/p/dcb/ban.jpg"');
				document.write(' border="0"');
				document.write(' alt="click for race info"></a>');
				break;
			}