Migrate from windows mail to outlook express

"For the messages use this method:

On the Vista computer, create a New Folder on the Desktop.
Open Windows Mail and position the window and New Folder so that you can see both.
Select the e-mail messages you want to go to Outlook Express, and drag them to the New Folder.
Put the new Folder onto removable media.
Attach the removable media to the XP computer.
Open Outlook Express and position the window and New Folder so that you can see both.
Open the New Folder and Select All.
Drag the selected messages into the list of messages for the Inbox or desired folder in Outlook Express (just make sure that the target folder is open).
Delete the New Folder from both computers and the removable media.

Source: Exporting Windows Mail back to Outlook Express"