Image Stretch

I have a page layout that has a series of thumbnails and one main image that is one of the thumbnails.
The thumbnails can be clicked and the main image is set to swap for the clicked image. The problem comes from the height of the main image that loads on the page. The size that the main starting image stays that same even though another thumbnail that is clicked requires different dimensions.

http://www.willmarairservice.com/testphp3.php?1990_Mooney_M20M_TLS_Bravo-11/

Code involved:
<table width="100%" border="0" cellpadding="5" cellspacing="0">
<tr>
<td valign="top"><?php if ($record): ?>
<?php foreach (getUploads($options['tableName'], 'uploads', $record['num']) as $upload): ?>
<?php if ($upload['hasThumbnail']): ?>
<img src="<?php echo $upload['thumbUrlPath'] ?>" width="<?php echo $upload['thumbWidth'] ?>" height="<?php echo $upload['thumbHeight'] ?>" border="0" onmousedown="MM_swapImage('picture','','<?php echo $upload['urlPath'] ?>',1)" />
<!-- <span class="t12_white"><?php echo $upload['info1'] ?></span><br />-->
<?php else: ?>
<a href="<?php echo $upload['urlPath'] ?>">Download <?php echo $upload['info1'] ?></a><br/>
<?php endif ?>
<?php endforeach ?> <br/></td>
</tr>
<tr>
<td valign="top"><img src="<?php echo $upload['urlPath'] ?>" name="picture" width="<?php echo $upload['width'] ?>" height="<?php echo $upload['height'] ?>" id="picture" /></td>
</tr>
</table>

OK the code above is old. I took off the width=" .... and height=" .... tags and it seems to work fine.

New Code:
<table width="100%" border="0" cellpadding="5" cellspacing="0">
<tr>
<td valign="top"><?php if ($record): ?>
<?php foreach (getUploads($options['tableName'], 'uploads', $record['num']) as $upload): ?>
<?php if ($upload['hasThumbnail']): ?>
<img src="<?php echo $upload['thumbUrlPath'] ?>" width="<?php echo $upload['thumbWidth'] ?>" height="<?php echo $upload['thumbHeight'] ?>" border="0" onmousedown="MM_swapImage('picture','','<?php echo $upload['urlPath'] ?>',1)" />
<!-- <span class="t12_white"><?php echo $upload['info1'] ?></span><br />-->
<?php else: ?>
<a href="<?php echo $upload['urlPath'] ?>">Download <?php echo $upload['info1'] ?></a><br/>
<?php endif ?>
<?php endforeach ?> <br/></td>
</tr>
<tr>
<td valign="top"><img src="<?php echo $upload['urlPath'] ?>" name="picture" " id="picture" /></td>
</tr>
</table>

Is there a way to set the sizes needed for each thumbnail clicked into the main image so it will not stretch or squish? Otherwise I will just keep it the way it is now.

Thanks