Hi,
read this carefully!!:
The only solution with Consistent backups of Domain Controller, SQL, Exchange and Co., on Windows 2003 and 2008, you must buy Veeam Backup !!
Otherwise take a "System State" Backup with ntbackup before you backup the DC with a other solution. When you restore a DC, make sure that you boot first into the "Directory Recovery Mode" and restore the "System State"!