//DETECTA NAVEGADOR Y S.O. DEL CLIENTE
function Is() 
{ 
var agent = navigator.userAgent.toLowerCase(); 
this.ns = ((agent.indexOf('mozilla')!=-1) && ((agent.indexOf('spoofer')==-1) && (agent.indexOf('compatible') ==-1))); 
this.ie = (agent.indexOf("msie") != -1); 
this.op = (agent.indexOf("opera") != -1); 
this.win = (agent.indexOf("win")!=-1); 
this.mac = (agent.indexOf("mac")!=-1); 
this.unix = (agent.indexOf("x11")!=-1); 
}
nS4 = (document.layers)? true:false
ie4 = (document.all)? true:false
nS6 = (document.getElementById)? true:false