Use a pen and paper. This accomplishes four things: 1) You don't write as much down during class. If you are writing all the time, you are not thinking enough. Period. Law school is done in your head, not on paper. 2) It forces you to revisit the material when you compile it into an outline EACH WEEK (now you can use the computer). 3) You won't screw around with IM'ing, surfing, etc. These are a huge distraction. And 4) You can't draw stuff easily on a computer. Law is conceptual and abstract. You'll want to draw arrows and pictures. Somebody will say, "yeah, but there's this great program that lets you draw on your laptop screen!" Yeah. And I generally use a snowplow to defrost my freezer.
The pen is your friend.