https://help.ubuntu.com/community/Ac...ryWinbindHowto seems to explain how to do what you want for Activedirectory domain, I assume it will be a similar process for a samba domain controller?
Its a bit of a daunting setup, but i read through it quickly and as far as i can make out once its all setup you login with " DOMAIN+username "
Quote:
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On the first login of a domain user a home directory will be created
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Then again I know absolutely squat about domains

I am a keen user of ubuntu thou and thought id do a quick search to help.