Have you ever run into a situation where you needed to join a new domain but keep the old profile? One of our senior engineers (Greg Prawl) provided this information to me the other day when I was doing a domain migration from SBS 2003 to SBS 2008. This process allows you to keep the old domain profile when you join a new domain.
This comes in handy because when you run the connect computer wizard (http://connect), you will only see local profiles. There is documentation out there that will suggest you create a local profile and then copy the domain profile information over to that local profile; however you can still lose settings and even worse time by following this method.
Here is an easy way to do this
Log into the machine as an administrator (domain/local)
Make a note of the profile that you want to keep (ie c:documents and settingsprofileyouwanttokeep)
Join them to the new domain (It will ask you for a username/password for the new domain, log in as an domain administrator).
Restart the computer (This does not remove the old domain profile)
Log them in under their domain account then log off. (This creates the new domain profile)
Log on as Administrator (of the domain) and add the domain user to the local administrators group.
Go into Regedit and go to (Start, Run, type regedit in the command line and click OK);
an you will see a lot of keys starting with S-1-5- etc. If you browse through them you will find these are the profiles stored on the PC. Look for the 'Profileimagepath' line and find the one with the profile you want to keep. Copy the entry and paste it over the new domain users account in the same field (ie c:documents and settingsnewdomainuser.domain).
Log off and log back on as the new domain user and you will have all the same settings desktop etc.
All you are doing basically is tricking the computer to use the original profile. The domain user MUST have the permissions set to be able to access the original profile, so please make sure that you either have them set as a local administrator or give them full permissions on the old domain folder.