It's easy to underestimate the 272 as most people know how to use Office and fall into the trap of thinking that it should be easy to troubleshoot it also. It's not a hard exam (not compared to many other MS exams anyway) but if you are unprepared for it then it's time for a visit from the fail ship!

(not having a dig btw John, I just like this picture

)
Outlook Express is certainly covered quite a lot in the MCDST course that I teach, as is Outlook.
I would recommend that you take a look at the
70-272 Objectives and make sure you are happy with all those topic areas. You can also see on that page the Outlook Express is featured quite a few times.