sinc users from NT to 2K Pro

We have a NT4.0 PDC and 3 NT4.0 BDC servers, we have added 6 win 2K pro pc to the network of 23 win 98 pc’s. Users move around to diferent pc’s.
How can we get the user manes and passwords from the win NT servers to the win 2K Pro pc’s. If one user changes there password on a 2K pro pc it changes on the servers, but not on the other 2K PRO PC’S. Help?