How can I get SID of windows user connecting to samba

[Karthikeyan]

Hi ,
    I have certain doubts in my understanding of the samba.
   please clear these issues for me .
   1,  The user name I give in windows box  for connection to my samba
server .will that user have a SID for it.
    if it has the SID. in samba where we storing that SID .
   2,   Is the user name we give in the windows box be validated in the
windows also or he will simply sent the password and user name to the
samba server.

with regards
karthik