Manual Mode: Works for Outlook 2000/2002/2003
Get into your Application Data folder to get at your .PST files which store all your Outlook data/emails.
You can usually get into the folder by typing %APPDATA%/Microsoft/Outlook (for Windows 9x/ME) or %USERPROFILE%/Local Settings/Application Data/Microsoft/Outlook (Windows 2000/XP)
Once there, you will see the PST files there. Copy the PST files to a location on another drive.
Export Mode for Outlook 2000:
Open Microsoft Outlook and select File>Import and Export>Export To File>.PST File and select the folders you want to export and the drive/folder you want to export it to, and you're done. When reinstalling/recovering data, select Import From File, point to this file and select the folders to import.
Data File Management Mode for Outlook 2002/2003:
The simplest way out! Create a new data container by selecting File>New>Outlook Data File. Create the file in another drive/folder. Follow the steps outlined in the previous Export Mode to export all current mails to this Data File. Now set the file to be the active container by selecting Tools>EMail Accounts>View or Change Existing Mail Accounts and selecting the container you just created in the "Deliver new mail to the following location" And voila, you have created a new Data File and configured it to be the active container. You can view the status of all data files you've created under File>Data File Management