Harringtons books are a MUST read... even if not right now then definitely once you get familiar with playing basic poker.
Forget Super System, this book was written 30+ years ago and is totally out of date. No offence to the Texas
Dolly but even he does not play poker that way very much now.
For SnGs there is no other book to read than Colin Moshman's Sit and Go Strategy book. This is the bible.
I am currently ordering Zen and the art of Poker. It was recommended me by Bill Seymour, long time Vegas tournament pro as the only poker book he ever read and is also a must read.
I would like to get Greenstein's Ace on the River but I believe this is an advanced book for things such as bank roll management etc and not much to do with playing and strategy at all... but I could be corrected here by someone who has read it.
Finally for live poker I STRONGLY recommend Joe Navarro's book read Em and Reap. I can't count the number of times I've folded or put players on a hand thanks to their body language. This book is leagues ahead of anything by Caro, but that is not to dismiss Caro, it just seems his stuff is very well known these days and probably doesn't need you to buy a book.