function popWindow( url, width, height, windowName ){
    //get center coords
	var left = (screen.width - width) / 2;
	var top = (screen.height - height) / 2;
	
	if (screen.height <= 600) {
		paramStr = 'toolbar=0,scrollbars=1,location=0,statusbar=0,menubar=0,resizable=0,width=' + width + ',height=520,left=' + left + ',top=' + top;
	 } else {
		paramStr = 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=' + width + ',height=' + height + ',left=' + left + ',top=' + top;
	 }
	 
	 window.open(url, windowName, paramStr);
}