[Slavok47]

Спасибо ребята! получил:
 <script type="text/javascript">   
      function loadIndividual(form) {
         if (document.images) {
            var gifName = form.individual.options[form.individual.selectedIndex].value;
            document.getElementById("img").src = 'catalog/' + gifName + '.gif';
			var gifTile = form.individual.options[form.individual.selectedIndex].text;
			document.getElementById("img").title = gifTile;
         }
      }   
      </script>