I've been doing my best to procrastinate taking all of these certification exams, so I finally had to just schedule and go, ready or not. So, a week after the 70-536 .NET exam and feeling a bit rusty with BizTalk 2004, I took 74-135, the BizTalk Server 2004 TS exam. Passing is 700, there are 40 questions and you have two hours max.
Fresh hands-on experience definitely helps with this test, as well as a lot of facts and useless knowledge like the command-line parameters to the management tools. Microsoft's expert test writers seem to believe that one will not have access to the product documentation to simply LOOK UP command-line parameters!
Having not laid a hand on BizTalk (2004) for at least three months, and having procrastinated studying again, I wasn't looking forward to test day, but I passed and it's done, so it was worth the trouble.
So how did I prepare (or not, in this case)? I read the first 300 pages of BizTalk 2004 Unleashed in the three evenings prior as a refresher. Beyond that I relied on my brief experience of 6-8 weeks earlier this year developing with BizTalk messaging and orchestrations, and I have done many BizTalk installs with both 2004 and 2006, not to mention debugging other peoples' BizTalk solutions.
The test manages to hit almost every aspect of BizTalk, including Messaging, Orchestrations, HWS, BAM, BAS, installation and management. That's why the hands-on experience is so important.