There is actually only one separate book, New Spring. And is about certain "main" characters in the (FIRST) few books, that leads up to the starting of Eye of the World. It happens 20 years before Eye of the world that is.
Its a matter of taste i'd say, u get plenty of things explained to you in New spring, that you also get explained to you in eye of the world, about the logics behind the world. But i would still say reading Eye of the World is the best choice, maybe you could go back and read New Spring after the three first books, if you arent already caught up and just gotta continue(the fourth one is one of the best ones in the series, and just saying its one of the best in the series, means that it is better than all the other really good books :P)
My advice would be picking up Eye of the World. Elsewise you might get attached to the wrong characters in the beginning, and some of the mystic might disappear.
Hf reading :)
I am afraid you have misunderstood the question.
They are talking about EotW put in two parts, From the Two Rivers and To the Blight.
To answer that, it doesnt really matter, they are the same. The only difference is that "From the Two Rivers" has a random chapter before the prologue added. It does not affect the story as a whole, but it gives a bit of a better understanding at the start (nothing you wont learn eventually)
So its up to you.
OK! :) Thank you to both of you. This helps a lot! I will be picking up Eye of the World tomorrow! I am very excited to start reading :D