Muxing WMA to AVI

[The Producer]

I have one soundless AVI, and one 5.1 WMA file.
Is there a way in Virtual Dub or any other program to
mux the two together?

The Producer

[ooops!]

As far as I am aware there is no application than can mux an .avi and a .wma file together.

However, why don't you have a go at encoding the .avi file to a .wmv file (using the WinMedia9 Encoder). Then mux the new .wmv and the .wma files together using the Windows Media Stream Editor.

You get quite good results doing it this way!