var popUpWindow = null;  
    function registerPopup(id)  
    {  	
            if(popUpWindow==null )    
            {
                popUpWindow=window.open('registerPopup.php?id=' + id,'subWindow','scrollbars=1,resizable=1,height=275,width=350,left=10');
                popUpWindow.focus();
                popUpWindow=null;
            }  
    }