Samba public share, without setting contents to 777?
I want to have a samba share set up so that any anonymous Windows XP user can read and write to the share without being prompted for a username or password. So far I have achieved this by using these options in my smb.conf
...and setting permissions for the shared directory and all it's contents to 777.
security = share
path = /some/path
writeable = yes
public = yes
776 and 766 don't work, and I feel like these are appropriate settings. What is the reason for last 7?
Is there a way to achieve this without setting to 777?