function Is() {
	var agent=navigator.userAgent.toLowerCase();
	var pos=agent.indexOf("netscape6");
	var str=agent.substr(pos);
	this.major=parseInt(navigator.appVersion);
	this.minor=parseFloat(navigator.appVersion);
	this.nc=((agent.indexOf('mozilla')!=-1) && ((agent.indexOf('spoofer')==-1)&&(agent.indexOf('compatible')==-1)));
	this.nc4b=(this.nc&&(this.minor<4.04));
	this.nc4=(this.nc&&(this.major>=4&&this.major<5.0));
	this.nc6b=(this.nc&&(this.major>=5)&&(str.search(/\/[\d.]+b/)!=-1));// Betas have "Netscape6/6.0bn", where n=1, 2, or 3
	this.nc6=(this.nc&&(this.major>=5));
	this.ie=(agent.indexOf("msie")!=-1);
	this.ie3=(this.ie&&(this.major==2));
	this.ie4=(this.ie&&(this.major>=4));
	this.op3=(agent.indexOf("opera")!=-1);
	this.win=(agent.indexOf("win")!=-1);
	this.mac=(agent.indexOf("mac")!=-1);
	this.unix=(agent.indexOf("x11")!=-1);
}
function setStyleSheet(is,ncStyleSheet,ieStyleSheet,nc6StyleSheet){
	var sheet="";
	if(is.ie4){
		sheet=ieStyleSheet;
	}else if(is.nc6){
		sheet=nc6StyleSheet;
	} else {
		sheet=ncStyleSheet;
	}
	document.write("<link rel=\"stylesheet\" type=\"text/css\" href=\""+sheet+"\">");	
}