I did this once, a couple of years ago. If memory serves: I installed
Thunderbird *for* *Windows* on my XP machine, and imported the .PST file into
Thunderbird under Windows. Then I transferred the Thunderbird profile to my
Ubuntu machine, and attached it to the Thunderbird installation under Ubuntu.

There's a proprietary Windows API that Thunderbird needs to import .PST files.

It doesn't pick up contacts, calendar information or tasks from Outlook.