I think what it comes down to is the Big Crunch vs Continual Expansion. Should the Big Crunch theory be correct, then perhaps the Big Bang is a result of the Big Crunch and this universe is in fact the hundredth odd such universal cycle, and one day it will stop expanding, collapse in on itself and set up another cycle. This is of course, the simple answer, and one which I like to use to avoid my brain imploding

But of course, it is not an answer, for an answer you need evidence and (thankfully, in a way) we have not received any evidence that the universe is beginning to slow in its expansion, however there is definately something older than the 'Big Bang' as has been recently found, so perhaps that echo is the echo of the universe before us?
Which raises the interesting question, which always makes me stop and think, and which Skybird has accurately pointed out, what was there BEFORE the first Big Bang? Brahmas first breath
I think that there are some questions to which we shall never find the answers, perhaps this is one of them, but of course it is an essential part of human nature, and one I think to be proud of, that we shall never stop trying to find the answer.