I get an error when I download and attempt to install the Northwind example database at:
http://www.microsoft.com/downloads/details.aspx familyid=06616212-0356-46a0-8da2-eebc53a68034&displaylang=en#top
Web Page Title: Northwind and pubs Sample Databases
The error is:
This installation package could not be opened.
Contact the application vendor to verify that this is
a valid Windows installer package.
Microsoft is the application vendor. Consider this to be "contacting".
I've tried both the Run option and saving the .msi file to my hard drive and installing from that. I've updated the installer software with a fresh download and install of that.
Any clues

Northwind for SQL Server Express Won't Install
tklose
Musta been sunspots ...