On my quest to encourage people to upgrade their certifications, I found a neat resource from the online Microsoft Certified Professional Magazine.
They have regular exam reviews that help you better understand what knowledge you need in order to be successful in your exam testing. They aren't braindumps, so don't expect see exam questions and answers, they're more of a guide detailing areas you need to be knowledgeable in.
If you're looking at getting MCITP Server or Enterprise certifications I can't think of a better place to start than with the 070-620 Configuring Microsoft Windows Vista Client. To get a jumpstart on preparing for the exam go to What MCPs Must Know About Configuring Vista .
You might also want to take a look at the official Microsoft exam prep guide 070-620 TS: Configuring Microsoft Windows Vista Client. The more information you have the better!!!
While you're at it you might want to sign up for a FREE Redmond Magazine subscription.