That decision is entirely up to you, in that there's no expectation that the Windows 2000 exams will be discontinued until after the next workstation/server version of Windows is released (probably no sooner than a year thereafter, in fact). Code-named "Longhorn" current intelligence on this version is that the desktop version will be released in 2006, followed a year or so later by the server version in 2007. Thus, 2008 is probably the earliest that the Windows 2000 exams would be discontinued, except possibly for 70-210 (Windows 2000 Professional) assuming that Longhorn desktop ships in 2006.
With that in mind, it should therefore make perfect sense to you when I tell you that the certification you finish first should be for the version of Windows that you're most likely to work with (or work with most) in your job. If that's Windows 2000, finish your Windows 2000 MCSE/MCSA. If it's Windows Server 2003, change your goals to meet that program's requirements. If you do take the Windows 2000 route first, remember that you can always take the upgrade exams--70-292 and 70-296--to upgrade your MCSE later on (and again you should be able to do this until 2008 or thereabouts).
This was first published in June 2004