For the MCSE on Windows 2000 credential:

Networking: An MCSE on Windows 2000 has the option to take only Exams 70-292 and 70-296, instead of all four core network exams; however, an MCSE on Windows 2000 can elect to take all four core network exams.
Client: An MCSE on Windows 2000 has already passed Exam 70-210 or 70-270, which also satisfies the client requirement for MCSE on Windows Server 2003; therefore, no action is required.
Design: The design skills required of an MCSE on Windows Server 2003 do not differ significantly from those required of an MCSE on Windows 2000; therefore, no action is required.
Elective: Elective exams are required so that candidates prove technical breadth, interoperability skills, or additional technical depth. For MCSEs on Windows 2000, the current MCSE credential satisfies the elective requirement for Windows Server 2003 because it proves the ability to support another version of the platform; therefore, no further action is required.

For the MCSE on Windows NT 4.0 credential:

Networking: The core networking skills required for the Windows Server 2003 are significantly different than those required for Windows NT 4.0; therefore, an MCSE on Windows NT 4.0 must prove their skills on all four core network exams.
Client: If the candidate has already taken either Exam 70-210 or 70-270, no further action is required.
Design: An MCSE on Windows NT 4.0 was not required to prove design skills, so they must prove their skills by passing either a Windows 2000 or Windows Server 2003 design exam. If the candidate has already taken a Windows 2000 design exam, no further action is required.
Elective: Elective exams are required so that candidates prove technical breadth, interoperability skills, or additional technical depth. For an MCSE on Window NT 4.0, the MCSE credential itself satisfies the elective requirement for Windows Server 2003 because it proves the ability to support another version of the platform; therefore no further action is required.

For the Microsoft Certified Systems Administrator (MCSA) on Window 2000 credential:

Networking: An MCSA on Windows 2000 has the option to take Exam 70-292 instead of Exams 70-290 and 70-291. However, Exams 70-293 and 70-294 are still required.
Client: An MCSA on Windows 2000 has already passed Exam 70-210 or 70-270, which also satisfies the client requirement for MCSE on Windows Server 2003; therefore, no action is required.
Design: The MCSA certification does not require candidates to prove design skills. To attain the MCSE on Windows Server 2003 certification, you must pass a design exam listed in the certification requirements above.
Elective: Elective exams are required so that candidates prove technical breadth, interoperability skills, or additional technical depth. For an MCSA on Windows 2000, the MCSAcredential itself satisfies the elective requirement for MCSE on Windows Server 2003 because it proves the ability to administer another version of the platform; therefore, no further action is required.