To be honest I don't find Computer Science books good in e-book form.
Its harder to flick through e-books and you'l want to use the books as a reference so I suggest pbook or hard backs.
CS is a huge field so it depends on what you're studying no books going to cover it all.
These 3 I own are often considered bible type books on their subject:
Introduction to algorithms - Cormen & Rivest
Artificial Intelligence A modern approach. - Russel Norvig
Introduction to computer graphics - Foley
They arn't really beginner books though despite the word "introduction" especially the first one.
Heres a link that you might find interesting:
http://www.cs.bris.ac.uk/admissions/what_is_cs/wics/
It talks about some interesting uses for CS.