Hi again,
Below is a skin1/customer/main/products.tpl file from 4.0.4. I included the code I mentioned above and it works fine when tested on my site (currently used for testing only). I am not using the "Buy Now" button either. Maybe having the entire file will help you, but if you use it, please make a backup of your current file.
{* $Id: products.tpl,v 1.45.2.1 2004/08/23 05:24:43 max Exp $ *}
{if $usertype eq "C" and $config.Appearance.products_per_row ne "" and $config.Appearance.products_per_row gt 0 and $config.Appearance.products_per_row lt 4 and ($featured eq "Y" or $config.Appearance.featured_only_multicolumn eq "N")}
{include file="customer/main/products_t.tpl" products=$products}
{else}
{if $products}
{section name=product loop=$products}
{assign var="discount" value=0}
<TABLE border="0" width="100%">
<TR><TD width="90" align="center" valign="top">
<A href="product.php?productid={$products[product].productid}&cat={$cat}&page={$navigation_page}">{i nclude file="product_thumbnail.tpl" productid=$products[product].productid image_x=$config.Appearance.thumbnail_width product=$products[product].product tmbn_url=$products[product].tmbn_url}
{$lng.lbl_see_details}</A>
</TD>
<TD valign="top">
<FONT class="ProductTitle">{$products[product].product}</FONT>
<FONT size="1">
{$products[product].descr|truncate:300:"...":true}
{if $products[product].avail > 0}
This item is available.
{else}
Sorry, this item has sold.
{/if}
</FONT>
<HR size="1" noshade width="100%" align="left">
{if $products[product].product_type eq "C"}
{include file="buttons/details.tpl" href="product.php?productid=`$products[product].productid`&cat=`$cat`&page=`$navigation_page`"}
{else}
{if $active_modules.Subscriptions ne "" and $products[product].catalogprice}
{include file="modules/Subscriptions/subscription_info_inlist.tpl"}
{else}
{if $products[product].taxed_price ne 0}
{if $products[product].list_price gt 0 and $products[product].taxed_price lt $products[product].list_price}
{math equation="100-(price/lprice)*100" price=$products[product].taxed_price lprice=$products[product].list_price format="%d" assign=discount}
{if $discount gt 0}
<FONT class="MarketPrice">{$lng.lbl_market_price}: <S>
{include file="currency.tpl" value=$products[product].list_price}
</S></FONT>
{/if}
{/if}
<FONT class="ProductPrice">{$lng.lbl_our_price}: {include file="currency.tpl" value=$products[product].taxed_price}</FONT><FONT class="MarketPrice">{include file="customer/main/alter_currency_value.tpl" alter_currency_value=$products[product].taxed_price}</FONT>{if $discount gt 0}, {$lng.lbl_save_price} {$discount}%{/if}
{if $products[product].taxes}
<TABLE border="0">
<TR>
<TD>[img]{$ImagesDir}/spacer.gif[/img]</TD>
<TD>{include file="customer/main/taxed_price.tpl" taxes=$products[product].taxes}
</TR>
</TABLE>
{/if}
{else}
<FONT class="ProductPrice">{$lng.lbl_enter_your_price}</FONT>
{/if}
{/if}
{if $usertype eq "C" and $config.Appearance.buynow_button_enabled eq "Y"}
{include file="customer/main/buy_now.tpl" product=$products[product]}
{/if}
{/if}
</TD></TR>
</TABLE>
{/section}
{else}
{$lng.txt_no_products_found}
{/if}
{/if}
Hope this helps,