Ways to Back Up Outlook 2000 Data 
There are several ways to create a duplicate copy of some or all of your data.
Personal Folders Backup
The new Personal Folders Backup feature lets you copy one or more personal folders (.pst) files to your hard disk or to a network location for safekeeping. And you can choose to get periodic reminders to do this. It's a breeze to retrieve backed up data, too. All you have to do is open the backup copy of the .pst file, and then move or copy items from it into your original file. It's the quickest and easiest way to back up all of your Outlook® data. Download Microsoft Outlook 2000 Personal Folders Backup.
Exporting
If you want to work with Outlook data in another program, but still keep the original data in your folders, export the data to another type of file, such as to a text file, which you can then import to another program. Or, to back up the data, export it to a .pst file. If you export specific folders rather than your entire .pst file, you'll keep the backup .pst file you're creating small, which is useful if you want to store it on a floppy disk. To keep the file even smaller, apply a filter to back up only specific items from each folder.
Archiving
If you want to remove items from your folders but not delete them, use an archive file. Periodically moving items from your main .pst file into an archive .pst file keeps your main file small and speeds up some operations, such as Find. You can use AutoArchive to automatically transfer old items into your archive file, or you can manually transfer old items by opening your archive file and dragging items from your main folders into your archive folders.
Copying the file to a set of floppy disks
A .pst file is usually too large to fit onto a single floppy disk. If you want to manually back up your entire .pst file to a set of floppy disks, use a disk splitting or compression utility such as Windows® Backup. For more information about copying files in Windows, see Windows Help.
Note For more information about either of these features, type the feature name in the Office Assistant or on the Answer Wizard tab in the Help window, and then click Search.