Definitely bumping silly sausage's recommendation here, MacBook Air's are so prevalent in universities because of their all-round versatility, especially their size/weight, battery life and performance.
TL:DR - Buy a MacBook Air, or if you hate Apple buy a Surface Pro 3 / Lenovo Yoga 2 /...
There are some really in-depth threads on reddit about this, such as:
http://www.reddit.com/r/LifeProTips/comments/1azes7/lpt_6_responses_to_when_an_interviewer_asks_you/
and
http://www.reddit.com/r/AskReddit/comments/1vcpy7/employers_of_reddit_during_an_interview_when_you/
hope...