if($forum_id != '42'
|| $forum_id != '43'
|| $forum_id != '44'
|| $forum_id != '45'
|| $forum_id != '46'
|| $forum_id != '47'
|| $forum_id != '48'
|| $forum_id != '49')
Couldn't this be written like this(if it fits your purpose??):
if($forum_id < '42' && $forum_id > '49')