I have Outlook 2003. I had to reformat a drive so replaced it with a new one keeping all the old data safe. I know where the old .pst files are but cannot import/load them into the fresh installation of Outlook 2003. Can anyone help please.

How are you trying to import them? I have to check, but I believe that the .pst files in Outlook 2003 are stored in

C:\Documents and Settings\[username]\Local Settings\Application Data\Microsoft\Outlook

Note that the Local Settings subdirectory is hidden. To show it, double click on TOOLS | FOLDER OPTIONS | VIEW (tab). Under "Hidden files and folders", click "Show hidden files and folders". Do this at the C:\Documents and Settings\[yourusername] subdirectory. You can optionally click "Apply to All Folders".

Once you get into the aforementioned folder, rename the existing .pst folder (example, rename Outlook.pst to Outlook.pst.original). Copy the old .pst file there ane see if it will open.