You would never be able to predict future states of the universe, simply because you cannot represent such states within the universe they represent. Without the ability to predict, the universe is effectively non-deterministic (literally, no one within it can determine its future states).
You make a good point. In my earlier post, replace "universe" with "solar system." Then, I can represent the states of the solar system in some subset of the universe, and I'll place this computer sufficiently far from the solar system so it doesn't interfere. Now I should be able to predict what happens on earth, unless you think that variables outside of our solar system significantly affect activities on earth, right?
1) Don't underestimate the butterfly effect. 2) We can already predict the future to a certain extent. 3) What you wish the universe was like is irrelevant. http://en.wikipedia.org/wiki/Wishful_thinking
Re 2: There should be an obvious qualitative difference between being able to predict where a ball will land if I throw it, and predicting who the passengers riding a particular train in 15 years will be.
Re 3: I was commenting on Roger Penrose's assumption that quantum must be "wrong" because it's "unintuitive" by expressing my opinion that I think quantum is more intuitive than deterministic theories. Indeed, Dr. Penrose and I are both using "wishful thinking," as did Einstein when he hypothesized that the speed of light is "constant in a vacuum." http://en.wikipedia.org/wiki/Speed_of_light#Special_relativi...
