Check the original vB navbar template for what you need:
Code:
<if condition="$show['member']">
<td class="vbmenu_control"><a href="search.php?$session[sessionurl]do=getnew" accesskey="2">$vbphrase[new_posts_nav]</a></td>
<else />
<td class="vbmenu_control"><a href="search.php?$session[sessionurl]do=getdaily" accesskey="2">$vbphrase[todays_posts]</a></td>
</if>
Tweak in your skin as desired.