Notes : Only Windows XP-Professional Edition can join the Domain, it does not work for WindowsXP-Home Edition.
Make sure that the workstation belonged to the same workgroup as the server and have a fixed IP address and hostname assigned.
Change the registry entry, run the command regedt32 and do the below
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\netlogon\parameters
"RequireSignOrSeal"=dword:00000000
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\System\CompatibleRUPSecurity
Use the Group Policy Editor (gpedit.msc) and enable “Computer Configuration\Administrative Templates\System\User Profiles\Do not check for user ownership of Roaming Profile Folders”.
Go to MyComputer right click Properties. Go to Change and click on Domain and enter the domain-name you want to join. When joining the domain for the First time enter userid as root and give the samba password. Make sure there is an entry for the root in the smbpasswd (samba password) file.
Reboot and then the changes will be effective.