Staz, I am also a CS student and had the same requirements as you, as indicated in
this thread and I decided to go with the iRex iLiad Book Edition which is the cheapest of the iRex devices. Honestly, in terms of screen size, it's pretty much a toss-up between the Sony Reader and the Kindle. However, I believe the Sony Reader has better PDF support and if you can get your PDF properly formatted for its screen, it would certainly look better than what Amazon could probably do.
See the thread above for screenshots of PDFs on the Kindle, kindly provided by Gideon.