Ok, ya got me pointed in the right direction. After looking at some other threads, this is the code I came up with, but all I seem to get is the default image. Definitely a newb at this, so maybe somebody can pick out what I'm doing wrong.
Code:
<div class="header">
<a href="$vboptions[forumhome].php$session[sessionurl_q]"><img src="<if condition="THIS_SCRIPT == ecdownloads">
images/twisteddark/misc/dlheader.gif<else />images/twisteddark/misc/header.gif</if>" border="0" alt="$vboptions[bbtitle]" /></a>
</div>