Well, here is my "answer". It uses the fact that String.Split can be told hold many items it should split to (which I found lacking in the other answers):
string theString = "Some Very Large String Here";
var array = theString.Split(new [] { ' ' }, 2); // return at most 2 parts
// note: be sure to check it's not an empty array
string firstElem = array[0];
// note: be sure to check length first
string restOfArray = array[1];
This is very similar to the Substring method, just by a different means.