I just got back from taking this test (ECE). I passed after only using instantcert. (no knowlege of OB prior except for taking psychology in high school a good 8 years ago)

Knowing who proposes what theories (and how they differ from other theories) was very key.

Also, there were alot of "situational" questions...such as what theory of leadership is Johnny using when he fires 10% of the workforce to maximize profits?

Good luck!