You personally may have a user name on the domain, This does not mean that any workstation you log on to will have an account.
To join a domain from a windows 2k pro workstation can involve 2 or 3 reboots,
First log onto the local machine with an administrative password, Then Right Click on 'My Computer' and select Properties, Select the 'Network Identification' tab, You will see the Computer name and the current Domain/Workgroup name and 2 buttons, Click the Properties button then Rename theComputer and if a Domain is selected click the Workgroup radio button and type in a group name ( any will do it is not going to be there long enough to register with the browse master) then click Ok, A dialog will tell you to reboot to make the changes, then click Ok on the System Properties Dialog, You will get the message to reboot now which you will need to do. When the system has started again log on to the machine as an administrator and repeat the Right click and properties select steps to the network ID tab, This time Select Domain and type in the Domain name for your network, When you click Ok a dialog will appear asking for a name and password for an account with rights to allow the machine to join the domain, When you provide these details and submit the form there will be a delay while the account is created You should then be presented with a message dialog saying 'Welcome to XXXXXXX domain' When you click Ok on this you will then get the Reboot to make these changes, Again keep clicking Ok and then reboot, This time when the machine starts there will be 3 entry boxes on the log on dialog, If you can only see 2 click on the 'Options' button and the 3rd one will either open or close. If you now provide your Domain Log-on name and password, Select the domain in the 3rd box you will be able to access the domain resources.