function reload(form){
  var strHref = location.href;
  var QueryString = location.href.substring ( location.href.indexOf ( "?" ) );
  var val=form.cat.options[form.cat.options.selectedIndex].value;
  
  QueryString = QueryString.split ( "&" );
  
  var i;
  
  for ( i = 0; i < QueryString.length; i++ ) {
  
    QueryString [ i ] = QueryString [ i ].split ( "=" );
  
  }

  self.location = strHref + '&cat=' + val;
}