Implement a large email archive on a Macbook Pro 13"
It really depends on what you're looking to optimize for, effort to implement or $$$ spent:

1) You could spring for Outlook for Mac which will know how to import your PST and will also make its contents indexable for spotlight.  Downsides include the $$$ and the memory overhead involved in launching Outlook when you want to get into the details of an old email you were looking for.

2) Use some conversion tool to get those emails into Apple Mail.  It will handle the quantity just fine (at least it does for my slightly smaller ~10G archive).  Spotlight integration is obvious here, but you also get quick view support when you use spotlight from a finder window.