Although, school is important, in this industry nothing hold more weight than experience! If you really want to be competitive, I would start working on your certifications. Most people will tell you to start with your MS Certs as they tend to be easier for new comers to the field but if you'd like a slightly more aggressive approach I'd start looking into getting your SANS or Cisco certifications.
As for your choice of major, that should be based on your primary interest or your intended career. Which ever route you decide to take, if you truly wish to be competitive in the field of pen-testing your are going to need a strong understanding and background both in networking/network protocols and computer programming (among other things).