$(function()
{
   $('a.a_help').click(function()
   {
      var href=$(this).attr('href');
      
      var dH=($(window).height()*2)/3;
      var dW=$(window).width()/2;
      $(window).each(function()
      {
         var helpwin=this.open(href,'helpwin',
            'scrollbars=yes,width='+dW+',height='+dH+', top=0, left='+$(window).width());
      });
      return false;
   });
});