“When the client logs onto the domain controller, it searches for a profile to download. Where do I put this default profile?”

First, the Samba server needs to be configured as a domain controller. This can be done by setting in smb.conf:

There must be a [netlogon] share that is world readable. It is a good idea to add a logon script to preset printer and drive connections. There is also a facility for automatically synchronizing the workstation time clock with that of the logon server (another good thing to do).