The New International Version is easier to understand, as it is written in modern English, but the King James Version is the one that most Christians use. I'd recommend trying to read two different versions together, if you have the time and/or inclination. I guess it mostly depends on what you want to get out of reading the bible: Do you just want to know what happens in it or are you interested in studying the historical context in which it was written and what it says about ancient cultures? I went through a phase in which I liked comparing different translations, trying to figure out which is the most accurate word for word translation,but now I feel like it was a totally pointless and time-wasting endeavor.
Lindsey (and Mallory), they do have a print copy of a parallel bible that each page has two columns, NIV (or any other version), and the KJV on the other. I'm not sure if B&N has a digital copy, but this is the easiest way to read and compare the two. If you CAN find a digital copy of this, try to see if they have a parallel STUDY bible, as this will have valuable commentary in details that will really help you understand what is going on. Some words and phrases will sound crazy, but with this little explanation it's much more understandable. I hope you find a good bible though.