[wmchale]

As an alternative:

•Select Tools | Options... from the menu in Windows Mail.
•Make sure you're on the General tab.
•Click Make Default under This application is NOT the default Mail handler.
•Note that selecting this will also make Windows Mail your default program for composing emails, for example. Do use the method above if you solely want to associate .eml files with Windows Mail.
Associate .EML Files and Attachments with Outlook Express
To make sure .eml files and attachments open in Outlook Express:

•Select Run... from the Start menu.
•Type "msimn /reg" under Open.
•Click OK.