hi - thanks for the reply - that method looks a little messy because the "guest" just get a vbulletin message "You are not logged in or you do not have permission to access this page. This could be due to one of several reasons:" etc etc with the login form
What I want is the system that folks like vbulletin.org use and forumshelp - see :
http://www.forumshelp.com/forums/f117/blue-steel-893/ and
https://vborg.vbsupport.ru/showthread.php?t=171951
where all guests can view the post but only registered/ paid people can download - you don't get ugly messages here
any ideas -- anyone ?