Configuration wizard for SQL 2008 Developers Training Kit stops

[Nam]

I installed and ran some of the demos of Microsoft SQL Server 2008 for
Developers Training Kit -- including creation of global alias and all common
databases.

Environment: Windows VISTA Business SP2 , MSSQL 2008 Express, MSSQL named
instance MyComputerName\SQLEXPRESS. No other instance is installed on my
machine.

Spatial Demo Configuration wizard fails telling me that I need to download
and install:
"Microsoft SQL Server for Developers Training Kit requires SQL Server
Adventure Works 2008 Sample Database"

I have AdventureWorks2008 and AdventureWorksDW2008 installed.

The problem is that that wizard stops on this step (the NEXT button is
inactive).
How can I figure it manually to make the wizard recognize the sample
databases on my machine?

What is the problem and how can I proceed with this Spatial demo?

Thank you in advance,
Nam