So today this new exam program launched "exam insurance" through which you pay a little more for your MSFT certification exam, then if you fail it you can take it again for free and if you pass it you get 25% off your next exam. I would tell you how much it costs... but it varies depending on where you buy it (you'll need to purchase through one of Microsoft Learning's training partners). This is a really good promotion if you're starting an exam track, or you know you're going to take a few exams in the near future.

Here's more on it: http://cacorner.blogspot.com/2006/11/exam-insurance-good-deal-gets-better.html