Moving users to a new domain is a real pain.  If the computers join a new domain, the users get spiffy new profiles.  Their old profiles may not be accessible.  That does not make users happy.

Another way is to use the Active Migration Tool. This tool enables you to migrate user objects (user accounts and groups), computer objects to the new domain.  Very useful when the company is splitting up, going through a divorce.

The users get to keep the profiles, the file server permissions remain intact.  Note ADMT has a 90% success rate for computer migration.

The only problem is selling it to the users that everything was migrated over and nothing was left behind!

1. On the client, reset the local admin account password. This is necessary in case migration fail to rejoin domain.
2. Set dns to the new domain DNS.
3. Launch Active Directory Migration Tool.
4. Launch workstation wizard. Follow the wizard.
5. When prompted about SID, choose replace.
6. For the rest of the questions, you can accept the suggested defaults.
7. At the last part you need to click close to actually start the migration.
8. Select pre-check and migrate and click start to actually start the migration.
The wizard will send an agent to \\client\admin$ to perform the migration.
a. If pre-check fail.
i. Disable firewall
ii. Enable file and printer sharing in TCP/IP properties.
9. Wait 20 minutes.
10. After migration reboot, change IP on the client to DHCP.
11. The wizard on the server should show all pass.

If the migration fails, login to the user computer as local admin.  Check the computer properties for the domain name.  If it is on the old domain, reset the computer account and rejoin the old domain.  Redo the migration.