For both MCSA and MCSE 2000 and 2003, 70-620 ("Big Vista" exam) can be used to satisfy:
In this post, I said that 620 can be used as a CLIENT ELECTIVE, but it is more accurate to say that it is one of your options for your CORE CLIENT ELECTIVES. Is that better? These updates should be reflected in the MCSA/MCSE requirements pages on MSCOM/learning momentarily.
UPDATE September 2007: 70-620 can be used for your Messaging and Security specializations too.