I think based on the last link in the thread below I think you could take exam 70-551 and get MCPD web because you are MCAD before MCSD however you must know that is not the upgrade path for MSCD per the upgrade chart in that link.
And I don't think exam 70-551 is retiring soon because the old MCAD and MCSD exams are still available till next year.
http://forums.msdn.microsoft.com/en-US/CertGeneral/thread/31da030e-67fb-496e-a37b-09c279d9752d
Asp.net MVP, MCPD Web C#, MCITP BI & MCTS SQL Server 2005