Outlook pre 2003 uses a diferent format data file.
You should allways have backups of your data, in the case of OL you can
either use the free backup addin available at MS site, or with OL *closed*
simply copy the *.pst file(s) - these are hidden files
When you upgrade to a later version, under normal circumstances OL continues
to use the same data file, if for some reason it doesnt, its a simple matter
to reconnect it.
However the upgrade process does not upgrade the data file to the new format
(unicode) this is more robust & doesnt have the max size problem that the
early version does.
So once OL is started & running ok, within OL, File>Add>Data File......this
will create a new format data file, you then copy data from the old file to
the new, dont use Import/export. Once done you close OL, then use OL Data
File Management, via mail icon in the control panel, or via the OL icon on
the desktop to set this new data file as the default msg store.
Once OL is opened you can then close the old data file (personal folders) or
leave it open