samba - Jul 2010 - Migrate windows 200 AD to Samba / LDAP

hi,

I want to migrate from Active Directory (Windows 2000 server) to Samba / 
LDAP (Ubuntu 10.4 LTS)

I followed these steps :

- Install Ubuntu 10.4 as BDC of the domain
- set SSID in Samba
- use net vampire process to extract information of AD
- Stop Windows 2000 server
- Restart Samba as PDC of the domain.

Now, Windows client were unable to connect to my domain.
Have I to pass client in WORKGROUP and add to my domain ?

I would like it to be transparent for computers, is it possible or I 
have to configure all computers again ?

Any idea ?