[Samba] Problem with samba and XP

[Tim]

I had Samba setup up on a debian box with three XP\2000 clients accessing the 
four samba shares but only allowing three users access to a couple of the  
folders. These 3 users had dummy accounts set up on the debian box (they 
never logged onto the debian box). The samba shares live on an external USB 
hard disk connected to the debian box (formatted as fat32).

For non (samba) related reason I have changed my OS to Mepis and now I can't 
seem to recreate the setup I previously had ( I did save my old smb.conf 
(along with 90% of my home folder) but that is now sat in a corrupt archive 
file which I can't access!!

At the moment my XP\2000 boxes can read and copy files from the samba shares 
but can't write to the Samba share which I want.

Below is my smb.conf, it may look a little messy as I have been trying things 
to get it working

Any suggestion please?

Tim

;*******************section global*****************
[global]

# Do something sensible when Samba crashes: mail the admin a backtrace
panic action = /usr/share/samba/panic-action %d
printing = cups
workgroup = home
server string = %h server (Samba %v)
hosts allow = 192.168.1.
socket options = TCP_NODELAY IPTOS_LOWDELAY 
log level = 1
dead time = 15
wins support = yes
hide unreadable = yes
passdb backend = tdbsam guest
dns proxy = no
max log size = 1000
restrict anonymous = no
domain master = no
preferred master = no
max protocol = NT
ldap ssl = No
server signing = Auto
oplocks = no
level2 oplocks = no
case sensitive = no
msdfs proxy = no
read only = no
security = share
;*******************section mit*****************
[Shared]
comment = /home/mit/Shared
path = /home/mit/Shared
guest ok = yes
;*******************section homes*****************
[homes]
comment = Home Directories
browseable = no
create mask = 0755
;*******************section printers*****************
[printers]
comment = All Printers
path = /tmp
browseable = no
printable = yes
guest ok = yes
create mask = 0700

[mp3]
guest ok = yes
path = /mnt/sda1/mp3/

[pictures]
guest ok = yes
path = /mnt/sda1/pictures
valid users = karen

[ZUNK]
path = /mnt/sda1/Zunk/
create mask = 0755
guest ok = yes