On the subject of getting yourself ready to the "Longhorn" Server upgrade exams, if you're already Windows Server 2000 certified your best path to "Longhorn" certification is to take the upgrade exams to get you to Windows Server 2003.
Exam 70-292: Managing and Maintaining a Microsoft Windows Server 2003 Environment for an MCSA Certified on Windows 2000
Exam 70-296: Planning, Implementing, and Maintaining a Microsoft Windows Server 2003 Environment for an MCSE Certified on Windows 2000
Note these exams will retire next year.
First, thank you for attending the part 1 of the Windows Server 2008 technical overview. From the comments