You didn't detail how this backup was accomplished.
For Outlook Express, if you make up a new backup method other that what we read at http://support.microsoft.com/default.aspx?scid=kb;EN-US;270670 then you have to TEST and develop how to get your data back.
I backed up my e-mail, address, incomming messages and put them in My Document file. When I try to open the backup file I get a message"not a valid Win 32 application. Can anyone tell me how to open this file so I can recover my e-mail?