As a voice technician, I've been working with both Cisco and Microsoft voice products. But as my company now wants to achieve the Voice Spec. partnership with MS, I had to put my Cisco CCIE books on the shelves for a few days.
Only a few days to study for the 74-924, is that all it takes?. No way! The Exam is one of the hardest exams I've taken so far (and I've taken a few). I feel this test really measured my knowledge and understanding of the OCS platform.
The reason why I passed with only a few days of studying is because I've been working with all of the products involved for several years, and have a thorough understanding of how Exchange, AD, PKI, NTP, DNS and Voice in general works.
I did not attend the Ignite course as recommended, but I really recommend attending the Ignite course if you do not feel you're to comfortable with all of the components I mentioned above. The Ignite course will take you through the basics (but not everything) you need to understand. In the end though, the only thing that will save your day is experience and in-depth knowledge.
This is a OCS 2007 exam, not a 2007 R2 exam. So know the difference (I know I missed a few because I've been studying R2). There will be a R2 UC Exam in April: 074-404