William,
This issue is a real pain, but it is quite easy to solve (if I understand your scenario).
The first case is when you just want to migrate one installation of DNN to new server.
What I do in such case (migrating one DNN installation to another) is
1. Backup the source DB
2. Copy the files of the source installation to the target FTP
3. Create a new DB in the target. Give it the same name of the source DB
(You don't have to give the same user/Pass since you can create a new one and change the web.config accordingly)
4. restore the target DB with the backup file you created from the source DB
5. create a new user (as I said I do not bother with the old one) and password in the restored DB (the target)
6. Change the connection string in restored site's web.config to have the new user and password as well as the new server address (do not change anything else in the web.config) do it for both connection string in the file
7. If the domain name is changed too You can also change the value in the portalalias table as needed. Change only the domain name value and keep portals ID.
That's it. start the site in the new location.
If you want to restore a table (not the whole portal) you can read the following thread which I think can give you good insight on how to do it.
http://www.sqlservercentral.com/Forums/Topic478210-338-1.aspx
(I may be off your question, if so, please try making it clearer)