[BirdOPrey5]

$post won't work in the header, $post is only defined inside a post... Also it the value of the poster not the value of the person viewing.

What you want is $bbuserinfo[field8], that holds the value of field8 for the user currently logged in.

As for the logic it would show

<div id="headerFill"><div id="headerL"></div><div id="headerR">

Only if the user specifically set this option to Yes. If it's set to "No" OR they never set the option it will show:

<div><a name="top" href="{vb:raw vboptions.forumhome}.php{vb:raw session.sessionurl_q}" class="logo-image"><img src="{vb:stylevar titleimage}" alt="{vb:rawphrase x_powered_by_vbulletin, {vb:raw vboptions.bbtitle}}" /></a></div>

instead.

This is good logic if you want users to have to "opt in" to this. If you wan't them to "opt-out" though (that is, display the first line unless they specifically said "No" then you'd be better off using the condition:

 <vb:if condition="$bbuserinfo[field8] != 'No'">

There's also the underlying issue that the header HTML is completely different than VB3 and I doubt any code you have for VB3 could work for VB4. VB4 has a stylevar for the banner background.