Show/Hide text and form field based on drop down selection

[Steve Speirs]

Hi

I'm trying to show/hide a simple piece of text and a text field on a
form based on what choice is made from a drop down box.

<select name="dropdown" size="1">
<option selected value="">Please make a selection</option>
<option value="1">Choice 1</option>
<option value="2">Choice 2</option>
<option value="3">Choice 3</option>
<option value="4">Other</option>
</select>

i.e. if Choice 2 is selected I'd like to display a new <tr> with the
following:

<tr>
<td>New text field:</td>
<td><input name="newField" type="text size="20"></td>
</tr>

if any other choices are made, I don't want to display anything.
I've tried several onchange() functions but can't achieve what I'm
looking for.

Any help would be appreciated,
Steve