Can't share my filesystem in RW using SMB

[metalwarrior]

Hi,

I'd like to share my NAS (FreeNAS) using SMB. That works fine in read-only.
However, I can't succeed to share my directories in read-write mode.
Here is my conf :
- the filesystem I want to share belongs to root:wheel
- I set "anonymous" access for accessing, read-only access via SMB is OK but impossible to write
- When I set to "local login", I can only log via SMB using a standard user, not root --> i.e. I don't have the write access on the filesystem

I really need to share the filesystem in read-write mode because I'm under Windows 7 Pro and I don't have any NFS client.
(This works very fine using NFS client from Linux - I have read-write rights).

Could you please guide me on how to share my filesystem via SMB so that the user that connects has root privileges ?

Thanks,

Metalwarrior