As someone who is not yet in law school, but has done my research, asked questions, etc, here is what I can tell you:
Undergrad will not prepare you for law school. Law school is different from undergrad. While in undergrad, keep your GPA as high as possible. SO major in something you will enjoy and do well in. That is half the equation. The other half is your LSAT.
By prepping correctly for the LSAT, you can increase your score as high as your mind can take you. Some will say that hard science majors tend to do better on the LSAT. That is true, but I believe it occurs because of self-selection. You don't have many slakcers majoring in chemistry. So take a major you enjoy, get a 3.9, and then worry about the LSAT