The power-score bibles explain this question in their books. They feel, and I agree, that your time is best spent by preparing specifically for the tasks on the lsat. while an intro to logic course may hit on some portions of logical arguments and the like, you will be dealt alot of extraneous info that is totally unrelated to the lsat. Like History of philosophy, the greek philosophers, and philosophical theories such as the divine command theory and natural law. Ive taken 2 logic courses at my school and they both covered about the same things, 99.9% of which will not help you for the lsat. At least that is my experience.