You've got no one to impress in law school with your Linux/hacker/phreaking/110011010 skills. Maybe you thought it was fun to have something different running on your PC during undergrad, maybe you were a CS major constantly writing scripts and various kind of code. You'll not be doing any of that in law school. You'll need Word in order to take notes, you'll need a browser to access class web contents and Westlaw, and you'll need Windows XP (as of this moment) to run the exam software. Just get a reliable PC and stop thinking that running Linux on your home PC is the coolest thing since sliced bread.
...But tell me the last time you saw a laptop being sold that didn't come with windows pre-installed.