Just look in the Properties of the root folder in your current profile. It
will tell you which file you are using when you click on "Advanced..."

Signature
Russ Valentine
[MVP-Outlook]
>I have a mailbox.pst and an outlook.pst file and I'm not sure which one I
> need to back up - I used to only have outlook.pst. Do I need both for
> abackup
> (to restsore my contacts info if anything happened) or just one of them?
> Thanks