Horizon - How Big Is the Universe

[skeeterm5]

I watched this the other night, quite a good program but it got me thinking and wondered if any other PHers had any insight;

1) Excepted theory is that the universe started at the Big Bang, a singularity which was a tiny (really tiny) point in space.

2) The Horizon program showed that current measurements "prove" the universe to be infinite in size

So I then started wondering when did the universe change from finite in size (singularity) and become infinite in size? Doing my head in trying to reason it....

S