Outlook Express data files are .dbx extention. These files are saved in one saparate folder, if you are using default path,
C:\Documents and Settings\Administrator\Local Settings\Application Data\Identities\{9598CB9E-6673-45B3-BB9A-F5FCCB3C40AD}\Microsoft\Outlook Express.
Local Settings-- is Hidden folder.
So You can take the DBX Folder backup from this path. Keep in DVD or CD.
After Your Windows OS loaded, copy this Folder In your c or d drive,
Go to Outlook Express, Options, Maintanance, Store folder, Give this path.
Then your mails will shown.