I have Outlook 2007.

I re-installed my computer and now I went to import all my old emails, only it didn't work. Went to File->Import and Export->Import from another program or file->Personal Folder file (.pst) and then selected my .pst file AAAND, it didn't work, it only imported some of the e-mails.

I never managed to figure out how to backup outlook so I ended up just copying all the emails to a folder and saving them so I've still got them.

2 questions (really is time to learn how to use outlook properly):

1.) What am I doing wrong with export import? Some of my backed up .pst files are large, some are small and I don't understand why. Specifically, my latest .pst is around 70 meg, the one that I save prior was 400meg, I imported both (and checked the option to not import duplicates), so I tried importing from prior .pst files but still nothing.

2.) If I can't get the .pst import to work, how do I import the emails that I backed up the dumb way into outlook without duplicates because my .pst import did import some really old emails?