Here is something you might want to do.
In showproduct.php place this line somewhere which will auto detect your thumbnail width and multiple it plus add a little space between the images and set the table width automatically aligned center.
$twidth = $Globals['previewwidth'] * 3 + 30;
Now edit your showproduct.tmpl and find this right above the $file1thumb etc calls and make the changes in bold
Code:
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