The MCDBA certification is pretty old at this point, as it is for SQL Server 2000.
You will want to look at these certs instead.
MCTS: SQL Server 2005
MCITP: Database Administrator
MCITP: Database Developer
MCTS: SQL Server 2008 Setup and Configuration
MCTS: SQL Server 2008 Database Development
MCITP: Database Administrator 2008
MCITP: Database Developer 2008
More information about these certifications can be found on Microsoft’s webpage.