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Microsoft Certifications
Microsoft certifications are a very popular option for those who have hands on experience working with the technologies being tested. The certification tracks are retired periodically, however, Microsoft offers upgrade paths to the current track and allows certified individuals to continue to use retired certifications. Microsoft has revamped their certification program and will be retiring the MCSE and MCSA designations. These have been replaced by the MCITP and MCTS designations respectively.

Editor's Notes:
At the time of this update, the Windows 2003 track will be the last of the MCSA and MCSE certifications, although no retirement date has yet been set. Windows 2008, Windows Vista and Windows 7 certifications are using the newer MCITP and MCTS certification tracks.

The table below outlines the different certifications available from Microsoft:

Certification Link Description
MCDST Official Site Microsoft Certified Desktop Support Technician (MCDST) is earned by passing 2 exams and is for those who troubleshoot Microsoft operating systems. This certification is geared toward helpdesk employees. This is an entry level certification.
MCTS Official Site Microsoft Certified Technology Specialist (MCTS) is an umbrella for a wide variety of certifications on specific products and technologies. Most MCTS certifications require 1 or 2 exams.
MCITP Official Site Microsoft Certified IT Professional (MCITP) is the replacement for the MCSE. Like the MCTS, the MCITP is an umbrella for certifications covering a wide variety of technologies. The number of exams varies by certification.
MCPD Official Site Microsoft Certified Professional Developer (MCPD) is an umbrella covering a number of Microsoft developer certifications centering around Visual Studio and ASP.NET.
MCM Official Site Microsoft Certified Master (MCM) is an advanced level certification that comes in 5 varieties: Exchange Server, Office Communications Server, Sharepoint Server, SQL Server, and Windows 2008 R2 Directory. To gain one of these certifications, you must attend the three-week training program and pass the corresponding computer-based exams and a qualifying lab exam.
MCA Official Site Microsoft Certified Architect (MCA) is the highest level of Microsoft certification. Currently 3 of the 5 MCM certs are offered and Microsoft plans to release Office Communications Server and Sharepoint Server in the future. To qualify, you must first have an MCM certification and pay $5,000 to appear before a peer review board.
MOS Official Site The Microsoft Office Specialist (MOS) certification offers 2 levels of certification: Specialist certifications require 1 exam and Master certifications require 4.

Official Resources:
Microsoft's web site can answer most of the questions that you have regarding their certifications, however, it is sometimes difficult to navigate so we have listed some of the more useful pages that you will want to check out.
Microsoft Certifications: Overview
Microsoft Certified Professional Member Site