Administrative rights

Hi

Here is my scenerio. I currently have a lab with an Windows 2000 Active Directory domain. I add a windows XP pro box to the domain and log in to the XP machine with a user who has Enterprise Admin rights on the domain except I have no rights whatsoever on the XP machine after logging in. Do I have to add the domain account to the local administrator account to have administrative rights on the XP machine. And if so why?

Any help would be greatly appreciated

dale