function center(url,w,h,sc) {

var l = (screen.width) ? (screen.width-w)/2 : 0; 
var t = (screen.height) ? (screen.height-h)/2 : 0;
pag=url;
if (navigator.appName != 'Microsoft Internet Explorer') 
str="screenX="+l+",screenY="+t+",outerWidth="+w+",outerHeight="+(h+30)+",status=no,toolbar=no,menubar=no,location=no,"+ sc;
 
else str="left="+l+",top="+t+",width="+w+",height="+h+",status=no,toolbar=no,menubar=no,location=no,scrollbars="+ sc; 

window.open (pag,'open', str);

}