Upgrade Outlook Express 5 to 6

I recently had a client who purchased two new computers and they came with XP and Outlook Express 6.0. I got stumped in trying to move her old folders and emails to the new machine. Manufacturer can back with recommendation that I had already tried. Outlook Express 6.0 has import options, but it seems to skip Outlook Express 5 as an option. Any words or wisdom?