Restore DC from tape

This is what we did on our DR drill:
1. Install the OS on the server.
2. Install remote agents for backup software.
3. Make sure that the OS is on the same SP level as the copy being restored.
4. Reboot the DC into Active Directory Restore Mode.
5. Restore only the C: drive and the system state to the original location. Make sure that the backup software is set to overwrite any existing files.
6. Reboot.
7. Work out any kinks that you may have here, which may include doing a repair install from the CD if the server hardware has changed any.
8. Restore the D: drive (presumably this is where Exchange is installed in your case).
9. Go into Exchange System Manager and on the Properties --> Database tab for each storage group check the box to allow database to be overwritten.
10. Resotre all Exchange stores and databases via yuor Exchange backup agent. Select to replay restored logs files only (this may be specific to Veritas).
11. Go back into ESM and uncheck the box to alow databases to be overwritten.
12. Mount databases and test.

If the hardware has changed significantly then there are additional steps. You can find them in KB263532 and KB321290 on Technet. All of the above assumes that this will be a non-authoritative restore onto the DC (i.e., you are restoring old AD data and other servers will replicate over the more current data once the server is restored). If you need to do an authoritative restore (i.e., you have no other AD data other than what's on the backup tape and this DC will overwrite other DCs) then you will need to follow the steps in KB241594 on Technet.

If you run into further problems (especially with different hardware) then post here and I've got a list of a bunch of registry keys that you can delete that will help.