Linux user account, and also manually change the Samba user account. Manually updating the password in three different locations is a minor headache that I would like to correct. I have been researching and
<snip> You *could* do it with openldap, with the WinDoze boxen authenticating through that. Now, I'll warn you that though it may have improved, a few years ago, openldap was a nightmare to configure, the documentation dreadull where it wasn't almost useless, and googling involved a *lot* of searching.
You may additionally have a look at smbldap-tools (available in the EPEL repository).
I had good experience with OS users authenticated by OpenLDAP on a Linux only network. It is not so hard to configure with authconfig. At the time I had a quick look at Samba integration and smbldap-tools seemed the way to go.
By the way, authconfig seems to also have options for smb / winbind: http://www.centos.org/docs/5/html/Deployment_Guide-en-US/s1-authconfig-comma... I never tried those though.