[JWait]

Well, the only difference I see is the part that has been commented out in your old code
{*{if $image_x ne 0} width="{$image_x}"{/if}
{if $image_y ne 0} height="{$image_y}"{/if}
*}
and
{$xcart_web_dir}{/if}/image.php?productid={$productid}
being changed to
{$xcart_web_dir}{/if}/image.php?type={$type|default:"T"}&id={$produc tid}
in the new code. The $type..."T" is the part that tells x-cart what image type and where to look for the image I believe.
I'm not sure what it is that you are trying to accomplish since even in the code that you got from x-cart the image size is undefined. Is it defined elsewhere, another template perhaps?