Problems connecting Windows XP Pro to Windows 2000 active directory

Hi all!

The Windrivers forums have never failed me in the past, so I'm hoping I can get an answer to this rather frustrating dilemma that I'm having:

I have a friend with a small business network setup in their office. They have a Windows 2000 server using active directory. They just bought a new machine with Windows XP Pro on it, and I'm trying to add it to the domain, but after it asks for the username and pasword of someone with the ability to add this user it keeps throwing the following error: "The specified domain either does not exist or could not be contacted"

Now, I can only even get this far if I specify the server's IP address as a DNS server in the TCP/IP properties. Otherwise, it won't even ask for a username or password, it will just say that the specified domain could not be found. So, I know it can at least query the server for a username and password (because if I enter an incorrect password, it will tell me so). but for some reason, after entering the username and password, it just churns for a little while, and then decides it can't contact the domain.

Any ideas would be most appreciated.