[jeeya]

{* $Id: product_thumbnail_cust.tpl,v 1.1 2006/01/19 13:35:09 max Exp $ *}
{include file="product_thumbnail.tpl" productid=$_imageid|default:$product.productid image_x=$config.Appearance.thumbnail_width product=$product.product tmbn_url=$product.tmbn_url}
{if $active_modules.Special_Offers ne "" and $product.have_offers}
{include file="modules/Special_Offers/customer/product_offer_thumb.tpl"}
{/if}

Use Above Code. It will also get your images aligned the way it suppose to in firefox browser.

Also if you want to remove background from productdetail page image too, just do same by editing product.tpl.