Joining and burning issue

I have two avi’s part 1 is 700Mb and part 2 is 698Mb but they have different audio bitrates. I have used VirtualDub to match the audio rates and the files have increased to 1.36Gig and 1.22Gig respectively when I joined them the new joined file jumped up to 105Gig!! Am I missing something simple that I am meant to do with this?

You forgot to check Direct Stream Copy on the video tab.

It is a [B]doublepost[/B] also!!!