PokerTracker

Simple question: when I make the conversion, do I automatically convert ALL databases or can I decide this on case-by-case basis?

Why this question? Because I have written some tools for two of my databases that require the DB to be Access.

You can decide what databases you want to convert. On the convert database window is a dropdown that contains all your Access db's, you get to pick which one to convert (PT only does one at a time).