getting audio of avi with 2 audio tracks

[E-Male]

i got an avi with 2 audio tarcks in it (1. ac3 2.0 english audio, 2. commentary) and need to extract the first audio track, but nandubdoesn´t work (produces an unusable file)
can anyone tell me how, maybe with a graphedit chain or something?
thx
e-male