samba - Nov 2006 - security at user level and public access

i'm following a book and i'm trying to setup a simple workgroup. it 
seems to be possible to set security at user level so i can have 
restricted access to some directories but also set guest allowed so i 
can have one directory accessible by everybody where i can share non 
important things.

but when i try to access the public folder still i need to login with a 
valid user. i created a dummy user that everybody can use, but is it 
possible to avoid this?

i know that it's a stupid question, can you just link me a page where i 
can learn it, if it's possible?

i'm using a ubuntu 6.06 server with samba 3.022

thanks,
            Davide