[Samba] [3.4.7] Right way to provide full access?

[Gilles]

Hello

	I'd like to configure Samba on a test host running Ubuntu so that I
have full read/write access from XP to a sub-directory of the root
filesystem.

The host is located on a LAN behind a firewall, so security is not an
issue, ie. I'd like to configure Samba with no/minimal security.

Currently, I can read but can't write. Between /etc/passwd, smb.conf,
and access rights to the actual directory, I'm a bit confused about
how to configure things.

Here are the files:
================= /etc/passwd
...
nobody:x:65534:65534:nobody:/nonexistent:/bin/sh
================= /etc/samba/smb.conf
[global]
workgroup = WORKGROUP
netbios name = LINUX
server string = Samba Server %v
security = user
guest account = nobody
; logs in /var/log/samba/
log level = 3

[share]
comment = Ubuntu File Server Share
path = /usr/src
browsable = yes
;access will be permitted as the default guest user
guest ok = yes
read only = no
create mask = 0755
available = yes
public = yes
writable = yes

================= ls -al /usr/
drwxr-xr-x  24 1003 users  4096 2011-05-06 13:10 src/
=================

Thank you.