Samba 3.020 file permission problems - cannot save to share from client

[TheBigPhish]

[global]
workgroup = [removed]
netbios name = [removed]
wins support = Yes
ldap ssl = no
invalid users = [removed]
valid users = @users
write list = @users
create mask = 0770
force create mode = 0770
directory mask = 0770
force directory mode = 0770
oplocks = No
level2 oplocks = No

[public]
path = /share/public
force group = users
read only = No
directory mask = 0755
directory security mask = 00
force directory security mode = 0777

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I recieved "file permission errors" trying to save to share from XP client (MS WORD), and cannot write to share. Admittedly, i'm not the best and unix file permission values, can someone possibly tell me what i am doing wrong? I have a feeling that there is one bit somewhere that needs to be changed, but i have been stuck trying to read the seemingly contradictory man pages & all the google'd topics i can find. I'm stuck.

[borromini]

Directory mask says '0755', which means read access, but no write access for users (drwxr-xr-x). Maybe that's the problem? Shouldn't it be 0775?