title: Fastest way to find out whether two ICollection<T> collections contain the same objects
body: <p>What is the fastest way to find out whether two <code>ICollection&lt;T&gt;</code> collections contain precisely the same entries? Brute force is clear, I was wondering if there is a more elegant method.</p>
  
  <p>We are using C# 2.0, so no extension methods if possible, please!</p>
  
  <p>Edit: the answer would be interesting both for ordered and unordered collections, and would hopefully be different for each.</p>