the thing that has always amused me about a limited universe theory is that it has only ever been limited by the strength of our telescopes. once apon a time the entire world consisted only of europe (or was it africa) and the sun spun around us.
and on another note; if the big bang is your answer for our existence, do you deny there being anything else before the bang? what about 3 trillion light years to the left, what was over there?