Yesterday morning I sat and passed the 70-293 exam. It was a tough one but I managed to score 844 points. As always I used the Microsoft Press book and a Transcender CD. This time I followed the advice of Transcender and downloaded the exam file from the website instead of using the file on the CDROM. The transcender questions were a lot more difficult than the real exam questions.
One thing that wasn't covered nearly enough in the book but which you should understand is certificate templates and the difference between version 1 and 2 templates.
A lot of the subjects should be familiar to you if you've passed 70-290 and 70-291. DNS and DHCP are repeated. This exam does pay more attention to WINS than the previous ones.
RRAS also comes back in this exam. Be sure you know exactly how it is decided wether or not a user has access at a specific time. Also study the various protocols and know which client supports what.
Clustering was also covered, study NLB and know the differences between unicast and multicast with one or two NICs and when you can expect NLB members to talk to eachother.
Have a look at real clustering and at least understand the various architectures and the way load balancing can be handled.
IPSEC, try it out, play with it, test it, get the hang of implementing it via policies.
Study everything you can find about certificates and their usage from mail signing to file encryption to smart cards. Know what rights are needed to perform admin tasks and know when you can and should use auto-enrolment and when you shouldn't.
The exam is hard but nowhere near impossible. From all the exams I've done so far this one and 70-284 I really do advise you to set up a lab and try a lot of things out!