pst is not a personal folders file?

I recently upgraded my 2k machine to XP, backing up my emails to a .pst file.

I am trying to import the .pst into Outlook and I keep getting the error “The file C:\Email\Backup.pst is not a personal folders file”

I am using the same exact version of Office 2002 on my XP machine that I was using on my 2k machine.

When I setup Outlook on my new machine, I specified New Outlook Data File to be a .pst file and to deliver new email to Personal Folders.

I tried running scanpst.exe several times and it still does not work.

Any suggestions?