Changing Submit button in a form.

This may seem simple to some of you, but I'm not very good at Javascript. I want to change the value of the submit button in my form depending on what selection is made from the drop down box.
Here's the code...

<form name="languagesel" method="POST">
<select name="s1" size="1">
<option>Select your language.</option>
<option value="main/m_english.html">English</option>
<option value="main/m_espanol.html" onSelect="languagesel.submitbox.value='Entra';">Español</option>
<option value="main/m_francais.html">Français</option>
<option value="main/m_portugues.html">Português</option>
<option value="main/m_deutsch.html">Deutsch</option>
<option value="main/m_nihongo.html">日本語</option>
</select>
<input name="submitbox" type="submit" value="Enter" />
</form>

Heh, I figured it out immediately after I posted that. Sorry.