You can easily backup your OE folders and restore the same after re-installing Windows. You need to just go this location where your OE folders are usually stored,

"C:\Documents & Settings\Administrator\Local Settings\Application Data\Identities\{SDOCE8ABD-5896-3E3D5}\Microsoft\Outlook Express"

Where 'Administrator' is the user's logon ID and the value in curly-brackets {} is an arbitrary string.

However, you also can go to "Tools menu and select "Options" and then select "Maintenance" tab, click the button "Store Folder" and copy the path, and paste the same to Windows Explorer to view the files.

Copy the important *.dbx files and save it to a different location and restore the same after re-installing Windows.

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Levin
Mail Recovery