Microsoft doesn't retire credentials any more: they just keep introducing new versions and giving their credentials very specific names. If you earn the MCSE.NET it will presumably become less and less relevant over time, and perhaps employers will start looking for people with an MCSE.NEXT (excuse the bad but unavoidable visual pun) instead. At that point it would be safe to say your MCSE.NET was more or less obsolete, but developers who know how to use current tools and can demonstrate strong on the job experience don't usually benefit as much from certification as those looking for their first or second jobs, or seeking to move up from programmer to senior programmer or architect positions.
Technically, your MCSD.NET will never be obsolete. But in terms of the good it does you in the workforce, it will probably be more or less irrelevant 5 or more years from now.
Although I didn't answer your question directly, I tried to answer it in a sensible way. If I've raised more questions than I've settled, though, do feel free to post again or to e-mail me directly at email@example.com.
This was first published in March 2004