look in contactus.tpl and change this bit
Code:
<tr valign=middle>
<td class=FormButton>{$lng.lbl_department}</td>
<td><font class=Star>*</font></td>
<td nowrap>
<select name=department>
<option value="All" selected>{$lng.lbl_all}</option>
<option value="Partners">{$lng.lbl_partners}</option>
<option value="Marketing / publicity">{$lng.lbl_marketing_publicity}</option>
<option value="Webdesign">{$lng.lbl_web_design}</option>
<option value="Sales">{$lng.lbl_sales}</option>
</select>
</td>
</tr>