[Samba] help with samba share: one write, many read

[myron]

I have a no-frill samba server that users can access their home  
directories from. Now,
I'd like to set up a share that contains a file that only I can write  
to, but anyone can read it.
I only seem to be able to do one or the other. If I can write to it,  
no one can read it. If everyone
can read it, I can't write to it.

I must be misunderstanding the settings of the options that I have  
available.

Everyone can read the file with these settings, but no one can write  
to it, including myself
[test]
path = /export/share/test/file.txt
read only = no
guest ok = yes

If I add the last two lines, then I can write to the file, but no one  
else can see the file any longer.
[test]
path = /export/share/test/file.txt
read only = no
guest ok = yes
write list = me
valid users = me

In both cases, I get a dialog box that requests access either as guest  
or registered user. Here's
the relevant global section.
[global]
        workgroup = METAR
        encrypt passwords = Yes
        smb passwd file =/usr/local/samba/private/smbpasswd
        map to guest = Bad user
        security = share
        preferred master = yes
        domain master = yes
        local master = yes
        os level = 255
        wins support = yes
        username level = 2
        use client driver = yes

Any help would be appreciated.
--myron
=================================
Myron Kowalski
MoCoSIN Network/Systems Administrator
Moravian College
myron at cs.moravian.edu