[devote]

<center><select name="vid">
    <option value="1">первый вариант</option>
    <option value="2">второй вариант</option>
    </select></center>
 
    <center><font color="#FFFFFF">Выберите:</font></center> 
     
    <center><select id="showfirst" name="size">
    <option>68</option>
    <option>74</option>
    </select>
     
    <select id="showsecond" class="hPd" name="size">
    <option>110</option>
    <option>116</option>
    </select>

<script src="http://code.jquery.com/jquery.min.js" type="text/javascript"></script>
<script type="text/javascript">
$(function(){
  $('[name="vid"]').change(function(){
    if (this.value == 1 ) {
      $("#showsecond").hide();
      $("#showfirst").show();
    } else if (this.value == 2 ) {
      $("#showfirst").hide();
      $("#showsecond").show();
      $("#showpants").hide();
      $("#showshoes").hide();
      $("#showcaps").hide();
    }
  });
});
</script>