A question about Bible translations

Agnostic here, I decided to finally dust off a bible I had laying around and read it through. My question is: are there significant theological differences between different editions of the bible? i.e, the King James Bible vs. any other edition? (As you can tell, I am utterly clueless.) If it helps, I have the "New World Translation," which I believe is the edition that Jahovah's Witnesses give out. Would it be a good idea to get a different edition, or can I make due with this?