I would put it within the else/last section:
PHP Code:
{else}
{*
<div class="welcome-img">
<a href="http://www.x-cart.com" target="_blank"><img src="{$AltImagesDir}/custom/welcome_picture.jpg" alt="X-Cart" title="" /></a>
</div>
*}
<!-- ZOOM SLIDER HTML CONTENT START -->
<div id="bannerscollection_zoominout_21">
... some skipped banner code ....
</div>
<p style="margin:0;padding:0;"> </p>
<!-- ZOOM SLIDER HTML CONTENT END -->
{/if}