[JWait]

I think the table that you have both search and login is "wrapping" to the next line.
Try this...

<TD class="HeadLine" height="22">
{if $usertype eq "C"}
{ include file="customer/search.tpl" }
{/if}
</TD>
<TD class="HeadLine" height="22">
{if $usertype eq "C"}
{ include file="login.tpl" }
{/if}
{* added to close cell and start categories in new cell *}
</TD></TR>
{* / added to close cell and start categories in new cell *}
<tr>
<td class="" width="100%">{include file="customer/hor_categories.tpl"}</td>
</tr>

++++++++++++++++++++
Since the "class" in the code above is blank ("") it will show as whatever your default text is, is that what you want?

Also, I don't understand why the table in hor_categories is only 430 px wide. That could be what is making the "gray bar" only go half way across the page. The blue line goes 100%.