<form>

<select name="menu">

<option selected value="../index.html">Главная</option>

<option value="../gb/">Гостевая</option>

<option value="../soft/">Загрузки</option>

</select>

<input type=button value="Ok" onclick="top.location.href=this.form. menu.options[this.form.menu.selectedIndex].value">

</form>