Conditional Statement Help

[MrEyes]

I am attempting to write a conditional statement for the header template, in plain english it would be:

if ("script == showthread" and "User Logged On" and "Thread Age > 30 Days") OR (forum ID == 33)
{
..output something
}
else if (no user logged on)
{
..output something
}

Now my stab at this is:

<if condition="in_array(THIS_SCRIPT, array(showthread)) AND $bbuserinfo['userid'] != 0 AND $threadinfo['dateline'] < (TIMENOW - 2419200) OR $forumid == 33">
..output something
<else />
<if condition="$bbuserinfo['userid'] == 0">
..output something
</if>
</if>

However this just doesnt seem to work right, and I can't see where