Registered users of this form and guests have exactly the same privelages i.e. you can only post to the guestbooks but can read everything else.
However, if you register you will be able to keep track of which items you have already read and which are new for easier browsing on future visits.
Any information you use to register will never be used by the site, and in particular will never be passed on to third parties.
As of July 2005 when you register you must wait until your are admin verified before your account becomes active. This should not take more than 24 hours or so but has regrettably become neccessary to stop spammers using the memberlist to advertise porn etc.