|There is no such thing as a bdc in Active Directory. PDC/BDC are nt4 terms which haven't applied in 10yrs.|
You have 2003 and 2008 servers yet are running 2000 AD? Someone hasn't been keeping up!
You can not add 2003 or 2008 unless you upgrade your AD. I would suggest starting with a 2003 upgrade.
To do this you need to run adprep for 2003. Google adprep 2003 for the details.
Once you have upgraded your schema you can now dcpromo the 2003 server to be a DC. I would suggest transferring all of the fsmo roles to it and both should be dns servers as well as global catalog holders.
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