Hey Jim,
I'm actually in the same boat as you...I wonder how much I have to know and how many games I'm losing (any? all of them?) because I am not playing "by the book". Everything I've heard about lower level players like me and you is to not worry about it but instead focus on tactics. I think that's been paying off for me lately...but still I wonder when I should start learning all these ridiculous names of openings and which one to play against which one.
I'm trying to improve my game and am wondering how important is a good working knowledge of all the different openings to achieve that goal.