First question: why use outlook if it it's apparently unwittingly. If you prefer Outlook Express, just keep using it and forget about Outlook or uninstall it.

Outlook Express has a File>Export, and Outlook has a File>Import. One of these should work, I think, if you'd rather switch to Outlook.

Some things I find unclear in your post:
"i copied the application data file": what file (or folder?) and to where did you copy it?
"unwittingly upgraded": that can only be done by installing certain varieties of MS Office, and be undone the same way
"copied the files across the there": what files from what to what?


Kees

Kees