It allows him or her to compose essays, presentations and use the internet for research or reference. Furthermore, computers allow another channel of communication with teachers or professors via email, so homework help or expertise is no longer out of reach when outside of the classroom.
As a hindrance to student life the computer can serve as a distraction from the task at hand. Due to its almost endless entertainment capability. Facebook or other websites such as Youtube or Hulu.com for instance, can serve a distraction and consume hours of a student's time that would otherwise be spent studying or doing homework.
--Speaking from personal experience, James F.