I need to change the domain on a few laptops and I would like to keep the existing profile intact instead of getting a new profile the next time the user logs in.
Is this possible?
You can't "keep" them as such, I don't think there's a command line "-Don'tMangleProfiles" command line switch for when you leave and re-join domains. Keep in mind that the accounts in the new domains will be totally new accounts that don't really have a connection to the old account.
However... if you look at this from a slightly different side, then it can be quite simple: what you can do is use the various "User State Migration" tools to essentially export the current profiles and then import them into the new accounts. (I can't be more specific because you haven't talked about the workstation OS and the exact process varies depending on that)
If we're talking about XP and Vista then this may be useful - Microsoft's free user state migration tool.
If you used something like ADMT to migrate the user and computer accounts between the domains, then the users will still be correctly mapped due to the sIdHistory attribute.
If that is not the case, you could try a tool like Reprofiler to reassign the user profile. I have not used this application, and it is possible that it may break installed applications in some unknown ways.
I've had to do this many times, it's a pain no matter how you do it. On Windows XP you can "copy" the domain profile to a local profile. Then unjoin the domain, and join the new domain, then "copy the new local profile to the new domain profile.
Here's the steps,
It's a huge pain I know, but this way, all settings, mapped drives, bookmarks, and software license keys!, will be copied to the new domain profile. In the long run this is easier then manually copying over a profile.
I tried ADMT and a few other tools and had problems with them. This was the solution I ended up relying on to switch over 30 workstations to new domain. You may run into a problem if a user installed software and selected "Me Only", it screws with permissions and the copy will fail, at which point you will have to run subinacl to restore permissions.
Also, the will not work on Windows 7, they disabled the functionality.
Just opinions here, no warranty or guarantees implied. Hope it helps.