You could try the
Microsoft certification[
^] path for becoming database administrator. They have a program for SQL2005 too and probably 2008 as well. There are plenty of books to be read on the subject. The number of exams and the exam numbers are listed
here[
^]. The
Self-Paced Training Kits[
^] for each exam can be found on sites such as Amazon.com.
When you got a number of related certificates you can call yourself a MCDBA, MCTS, MCPD or whatever, depending on what certificates you got.
Of course those certificates are only a formality and they look good on your resume. I think you can be a good database admin without having any certificates whatsoever. But they are a good way to prove yourself and show that you have put time in learning.