function CenterPopUp(url, name, height, width)
{
var w = 480, h = 340;

// calculate screen width and height.
if (document.all || document.layers) {
w = screen.availWidth;
h = screen.availHeight;
}

var leftPos = (w-width)/2, topPos = (h-height)/2;

// open the selected Url in a new browser window.
window.open(url, name,'resizable=yes,status=yes,titlebar=no,scrollbars=yes,width=' + width + ',height=' + height + ',top=' + topPos + ',left=' + leftPos);
}