It is possible to authenticate your FC2 box against your SME server using winbind. Try "authconfig" on your linux box. I struggled with this over the past couple of days but got it working today.
I had to use
client schannel = no
in the smb.conf on the linux client.
With winbind, I was able to get the authentication working, but that still leaves the file access question. I'd like to see the authentication move to LDAP and then I could add NFS to have a complete solution.
I use linux on the desktop a lot and just started playing with SME server. to integrate linux workstations, LDAP authentication is really the right way to go. Is anyone working on this? I'd like to help. I am pretty familiar with Samba/LDAP