var agt=navigator.userAgent.toLowerCase(); 
var is_major = parseInt(navigator.appVersion); 
var is_minor = parseFloat(navigator.appVersion); 
var is_nav  = ((agt.indexOf('mozilla')!=-1) && (agt.indexOf('spoofer')==-1) 
                && (agt.indexOf('compatible') == -1) && (agt.indexOf('opera')==-1) 
                && (agt.indexOf('webtv')==-1)); 
var is_nav2 = (is_nav && (is_major == 2)); 
var is_nav3 = (is_nav && (is_major == 3)); 
var is_nav4 = (is_nav && (is_major == 4)); 
var is_nav4up = (is_nav && (is_major >= 4)); 
var is_ie   = (agt.indexOf("msie") != -1); 
var is_ie4up  = (is_ie  && (is_major >= 4)); 
var is_mac    = (agt.indexOf("mac")!=-1);
 
if ((agt.indexOf("msie") != -1) && (agt.indexOf("mac") == -1)) {
 var newwindow;
}
function centerPopUpWin(textlink,wd,ht) {
	newwindow = window.open(textlink,'popup',config ='height=' + ht + ',width=' + wd +',scrollbars=yes,toolbar=no,copyhistory=no,resizable=no,directories=no,menubar=no,status=no,location=no');
	newwindow.moveTo( (screen.availWidth-wd)/2, (screen.availHeight-ht)/2 );
	newwindow.focus();
}