If you are talking about Outlook XP (not Express) you will find it clicking in Outlook on file -> data folder (or something like that) -> Open the working folder (or something like that). Browsing to that folder will be slightly tough, since it's located in some hidden folders.
I don't know how to import the outlook.pst to apples mail.app anymore, but I did succeed (2002 ). I was googling for this and found a step by step instruction. Unfortunately I didn't save it and don't remember the site, but once I find it again, I will come back to this thread and post it..
iBook 600; 12''; 640mb; 8mb Rage; DVD-CDRW-Combo, 20GB
P4 1.6; 2x80GB Raid1 (file-server)
tiBook 1Ghz, Superdrive, 768MB, 64mb 9000, 60GB