83-640 will gradually replace 70-640？？

Firstly, my answer is yes. However it does depend on where you are and what language you’re taking the exam in.
MCTS 83-640: Configuring Windows Server 2008 Active Directory is the first Virtual Lab-based exam, which is part of the MCTS track, an alternative to taking 70-640. Currently available in English only, the exam is gradually rolling out to different countries through 2009. It emphasizes a practical skills assessment that complements the traditional multiple-choice format.
 It will be seen from this that 83-640 will gradually replace the current version of the Exam 70-640 in English .It is said that 83-640 has been rolled out in New Zealand, Ireland, Singapore, and Canada. And the candidates in some areas can take either of 70-640 and 83-640, but in some countries in English language 70-640 has been replaced of 83-640. In other countries where 83-640 hasn’t been released, test-takers will take 70-640. Although it’s not yet released in the U.S., to be sure, the new emulation test (83-640) is scheduled to replace 70-640 completely as testing centers support the format.
83-640 versus 70-640:
The same point:
  83-640 maps to the same objectives as 70-640, but this version (where available) contains a Performance Based component in addition to the standard exam item types. You can take either exam; they both give you the same qualification.
The differences or changes:
The study objectives or content are the same for both exams, just the format has changed.70-640 is the traditional question based exam, 83-640 is a virtual lab based exam testing actual practical knowledge .The format of 83-640 still includes traditional multiple-choice item types. Because Microsoft does not plan to discontinue that type of question at this time, since some points are better tested in a question/answer format than by demonstrating a technique. However, 83-640 is a lab-based exam, please remember. In a word, the format of 83-640 is divided into 2 sections:
1.2 Labs with 10 more or less Tasks each. (Do Practices on DNS, Group Policies, Active directory sites and Services, functional levels, Domain Trust & Computers, Changing Type of Active directory Groups from one to another)
2. 30 question multiple choices.
Besides, the duration for 83-640 is about 4 hours.
3. How to prepare 83-640?
1.70-640 MS Press books are they OK for Exam 83-640???
In some countries ,70-640 has been changed to 83-640 .Now，There aren’t any  classroom training ,Microsoft E-Learning training and Microsoft Press books for 83-640 currently available. Many candidates don’t know how to study or prepare 83-640.There are confusion among them that whether 70-640 MS Press books, online resources, practice exams or e-learning training are still valid for Exam 83-640.Here, I have a piece of advice for those candidates for 83-640.Whether 70-640 exam or 83-640, both of them are about TS: Windows Server 2008 Active Directory, Configuring. They have the same objectives or main topic area. There are no books for 83-640 available. Ms Press books for 70-640 are best books for 83-640 candidates to study the theory. Because MCTS 83-640 is a lab-based exam and harder than 70-640 exam , in my opinion, to pass 83-640, it is key to do practice and practice, practice, especially labs.
2. There are some experiences in 83-640 from those passing the exam or get highest scores.
Hope you can get useful information for you to study 83-640.
1.    One with a 900 score in 83-640 said that he had read thoroughly MS press 70-640 only and do a lot of practice and labs .More important, make sure you PRACTICE the labs before you’re in the test.
2.    One pass 83- 640 exams with 866 scores said that he used Exam Cram 70-640 book, CBT Nugs and a little 3 server lab environment with Virtual Server and the VHD’s available from MS’ website. Two lab and they where pretty hard. Since he was not working with AD. But you can use HELP from the Windows 2008 server and that made it for him!
Finally, I recommended the following article, in my opinion, which is worth your reading, and helpful for us to know better 83-640.
Skills Development Crucial for IT Pros