Really the last two things I use it for are games and my irrational attachment to a 2 GB Outlook file containing stuff I will probably never look at again.
You can convert all your outlook emails to .eml files and import them into Thuderbird or whichever other client you use.
there is a linux package called readpst that, as its names suggests, read's the contents of the PST and can output into mailbox or maildir formats. Thunderbird seems to be happy with its default output