Ok Those of you who are MCITP:SA or EA  I have a couple of questions.
SCENARIO:
I have a great co-worker/friend(whats up 
technowiz  
 ) trying to motivate me to finish up my MCITP:SA EA.  He is willing to humilate himself at work (he will knock on all of the IT manager's office doors call them into the common areas stand on a desk, beat his chest and declare that I am the man!!) so long as I finish the SA track by the end of the year (640,642,646).  I have already finished up 70-620 (big whoop) for the EA track.  So Basically this means I have to study,take and pass an exam every month.
QUESTIONS:What is the biggest bang for buck purchase in study material?  
I already have the  MCITP:Training Kit but I need to expedite the studying and was considering Exam Cram.
Which exam has been the easiest for you and why(640,642, or 646)? I want to maximize study time by knocking out the easiest exam first.  the AD exam is the first choice on the MCITP exam roadmap.  But AD is one of the last exams for the MCSE track and one of the hardest to my understanding.
Also has anyone been up against a timetable like this? (3exams 3 months no 08 experience)
Your assistance is greatly appreciated