Is the Domain name in question actually a registered Domain or did you just make it up and add it to your server?
You must have a NS record at the registrar(pointing to server where Domain is hosted) or on the host machine that the name is pointing to, if it isnt the only way to point it to that name would be to edit your hosts file
and add the line
xxx being the IP of the server you are trying to hit.
could also be that vista is rubbish, espc when connected to svr2003.
One of my clients wanted a new pc and had to be connected to his 2k3 domain, after a lot of strong encouragement he decided that me wanted xp on it as vista has problems with 2k3 as it was designed to run on 2k8
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