SAMBA Domain Controller

Samba Domain on XP:

Start->run->MMC
->File->add/remove snap-in->Add
-->Add
--->Group Policy Object Editor->Add
---->(Group Policy Object must be 'Local Computer')->Finish
--->Close
-->OK
->Local Computer Policy
->Computer Configuration
->Windows Settings
->Security Settings
->Local Policies
->Security Options
->Disable "Domain Member: Digitally encrypt or sign secure channel data (always)"
Restart, and you should be able to log on with your Samba username and password.