Replacing old 2000 domain with 2003 domain

Hi

I have a nice task ahead. replacing our old and malfunctioning 2000 Domain with a new set of domain controllers and i complete new AD design and a diffrent role setup.

Normaly when upgrading i just install a new 2003 server and prepare the servers (forestprep + domain prep + dcpromo) and transfer all roles to the new servers and then depromote the old 2000 servers.

BUT

now sinc this domain/AD has some serious problems, we need to set up new roles.

I see some obvious problems beside the users management, thatis all the service accounts.

Is there a good practice of doing this upgrade? Transfering some data from the old AD?

And then how can you easily apply the new domain to all clients? Approx 500.

Best Regards Andr?