Is it possible to generate (highly probable) unique Integer from GUIDs?
int i = Guid.NewGuid().GetHashCode();
int j = BitConverter.ToInt32(Guid.NewGuid().ToByteArray(), 0);
Eric Lippert did a very interesting (as always) post about the probability of hash collisions.
You should read it all but he concluded with this very illustrative graphic:
Related to your specific question, I would also go with
GetHashCode since collisions will be unavoidable either way.