daveVk - 1:21 am on Apr 16, 2012 (gmt 0)

Start by stripping html to essentuals

eg

<div class = "thumbnail_1" id = "thumbnail_1">
<a href="javascript:void(0);"><img style="border: 0pt none;" alt="" src="images/czech_page/czech_thumb_1.jpg" onClick = "change_images('image1', 'description_1')"></a>
</div><!--END OF thumbnail_1 -->

becomes


<div><img class="noBorder" alt="" src="images/czech_page/czech_thumb_1.jpg" ></div>

same for main images

<div><img src = "images/czech_page/czech_full_1.png" alt = "" ><p><b>this is image 1.</b></p></div>

I included the image and associated paragraph in a div to make pair easier to identify.

On page load you need to attach onclick handler to each of thumbnails such that nth thumbnail div effects nth image div.