"at the point where I need a prep-course". Have you taken the exam before? If so, what were your weak points? Or are you looking at taking a prep-course so you will do well?
I took boards boot camp. While the voice on the videos could be somewhat boring at times, the information and the way it was laid out was pretty good. All I can say is I passed first try and did better than I did on level 1 (which I also passed first try without a prep course). And really didn't put too much work into it other than follow the plan laid out by BBC (it probably just didn't seem like much work since the plan is laid out for a few months of work via a couple hours a day). I didn't even have much time for their question bank and only did a few hundred questions.
I can't say anything about other prep courses as I didn't take them. Sorry.
Oh - and I took the "new" scoring exam in August 2009.