I had the opportunity to fully backup and restore an Active Directory controller last week.
These notes are probably not specific to Windows Server 2003, but if you aren't using 2K3 don't take these as law. YMMV, as always.
Here's a couple of important points:
Use NTBackup – it works well, and can be pointed at a network share. Use another solution if you want, but _also_ back up the server with NTBackup.
Make note of the Service Pack level, and ensure that you have that service pack install file available. When you re-install Windows you must re-install the SP before you perform the restore.
Don't forget to perform the restore in "Directory Services Restore Mode". It's not necessary to perform the backup this way, just the restore.
Also, when setting up a server for the first time, make sure you have a large enough C: drive. This is what prompted our backup/restore session. Note that many Dell servers are shipped with a 20Gig or smaller C: partition… generally, this is way too small.
I recommend that you make your C: partition as large as possible, unless you have specific reasons not to.
