The Large arrow.. while holding down the button, move the cursor back to middle. The map starts to "hover" and move slowly.. That's where you can get fine-tune movement.
This is not obvious that this is possible, I totally know where you're coming from. Actually I was upstaged a bit not that long ago by a guy who hired me to teach MapPoint to his customers when he butted in to point this out to the class in response to a question I failed to answer properly..
Eric