[Samba] Can't get guest users to see a drive without logging in

[Scott Simpson]

I have a drive set up like

[public]
   comment = Public drive for miscellaneous stuff
   path = /apps/local/public
   writable = yes
   guest ok = yes
   force user = root
   force group = engr
   create mask = 0664
   directory mask = 0775
   public = yes
   browseable = yes

and I want users without Unix accounts to be able to access this drive
from 
Windows machines. However, whenever they try to access the drive it asks
for 
a login password. Users with Linux accounts on the machine aren't asked
for 
the password. How can I let in guest users without Linux accounts?
Thanks.