DivX to DVD, I can't get audio!

[Digitales]

All the DivX files I have downloaded from the web seem to have MPEGLAYER3 (MP3) audio, when I try to make the files into a dvd the video works fine but with no sound at all.
Do I have to change the audio file type? the divx plays fine on the pc, but when i take the file into Sony dvd architect it can't recognise the audio, even though i have codecs which will play it back.
What am I doing wrong? and what apps do i need to sort the sound out in order to make the file into a dvd???

Thanks for any help...

[setarip]

The audio is probably Variable Bitrate .MP3 ("VBR"), which most authoring programs don't "like".

Using VirtualDubMOD to Convert "VBR" .MP3 to Uncompressed .WAV

1) Load the .AVI file into VirtualDubMOD (a different program than the standard VirtualDub)

2) From the "Video" dropdown menu, select "Direct Stream Copy"

3) From the "Streams" dropdown menu, select "Stream List" - and rightclick on the audio stream, then select "Full Processing Mode" - then click on "OK"

4) From the "File" dropdown menu, save .AVI with a new filename