I would be interested in this also. I am currently working with IDR and trying to include it in the disaster recovery plan.
From my experiments with Windows 2003 and SQL 2000, here is what I found. When you make a full backup of the server, you can either backup the SQL database through the System State, or just the SQL databases by themselves.
If you backup the SQL databases by themselves, IDR will not restore the SQL databases. The documentation says that only the defauly databases will be restored, and all user created databases will have to be restore manually. Perhaps my backup was corrupted, but the master database was not restored which won't let the SQL server start. During IDR, I tried tor restore the databases manually, but since there is no SQL server running, the databases could not be restored.
Now if the SQL databases were backed from within the System State, then during IDR, the databases will be restored. So when the system comes up, it will have SQL running with the last full backup (or whenever the IDR CD was created). Then you will have to restore additional data manually.
So my guess is to backup the SQL databases with the System State, so that when you are running IDR, the databases will be loaded, and atleast SQL will be operational.