Note the .com name in the above link. If that isn't a tell, I don't know what is.
Of course, you could just back up the data, .dbx files, but that was in my Windows 98 system. The trouble is the .dbx format is proprietary to Microsoft.
To find the data files .dbx files in Outlook Express, click
Tools > Options > Maintenance > Store Folder. Clicking the Store Folder button will open a box with the pathway to your data files.
I know you could copy and save the folders to Outlook Express by finding the data files and the Outlook Express folder, but I'm not sure you could reinstall it, because of the registry. Maybe someone else can address that question.