var Is = new Object();
	Is.agt = navigator.userAgent.toLowerCase();
    Is.major = parseInt(navigator.appVersion);
    Is.minor = parseFloat(navigator.appVersion);
	Is.macIE5 = (Is.agt.indexOf("mac")!=-1 && (Is.major == 4) && (Is.agt.indexOf("msie 5")!=-1));
	Is.nav =  ((Is.agt.indexOf('mozilla')!=-1) && (Is.agt.indexOf('spoofer')==-1) && (Is.agt.indexOf('compatible') == -1) && (Is.agt.indexOf('opera')==-1) && (Is.agt.indexOf('webtv')==-1));
	Is.nav5up = (Is.nav && (Is.major >= 5));
	Is.nav4 = (Is.nav && document.layers);

	if(Is.nav4)
	{
		document.write('<link href="css/netscape4.css" rel="stylesheet" type="text/css">');
	}