If you're going for the MCDBA cert, may I offer a piece of advice?

There are (or were) two OS tests as part of the MCDBA.  Windows 2000 Server & Professional.  I don't know if MS has changed that to 2003 Server & XP or if it's still the same.  Regardless, whatever other order you may study for and take your SQL tests in, study for the Server OS test BEFORE you study for the PC OS test.  If you can get all the info for the Server OS test in your head (and understand it), then you should be able to pass BOTH tests with flying colors. 

That's how it worked for me when I got my MCDBA.  I studied for the Server OS test before the PC OS test because I thought (rightly so) that the Server OS was going to be harder.  I passed both tests within a week of each other because the PC OS test had essentially the same things on it that the Server OS test did, only it was a lot less.  If you know what I mean.

Anyway, I hope this advice helps out anyone going for the MCDBA.