This form will redirect the user to this url: http://google.com/search?q=SEARCHQUERY&tbm=TYPEOFSEARCH No JavaScript needed! :)

look_ma_no_js.html

<form action="http://google.com/search" method="GET">
  <fieldset>
    <legend>Search using google</legend>
    
    <label>
      My Search Query
      <input type="text" name="q" />
    </label>
    
    <label>
      What do you want to search?
      <select name="tbm">
        <option value="isch">Images</option>
        <option value="vid">Videos</option>
        <option value="shop">Products to buy</option>
      </select>
    </label>
  </fieldset>
  
  <div class="buttons">
    <input type="submit" value="Search in Google!" />
  </div>
</form>