You do need to be familiar with the new 2008 features. Whether Transcender's good enough, I can't say. Never seen their test exam.
Check the requirements list on the MS website and make sure you're comfortable with all the sections.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability