Does following:

You set up folder with input AVI files and folder for result.
You create (or use my reference) templates for VirtualDub script where use <INAVI>, <OUTAVI> and <OUTWAV> tags instead of names of input AVI, output AVI and output WAV.
Run application, it creates .JOBS file wich is compatible with VirtualDub.jobs (you may overwrite it and whole queue will appear in Job Control window), created output folders if needed.
Then select "Run script" or "Job Control" menu item in VirtualDub and wait for result :)

These templates are included:

1. For files that contains both video and ausio streams:

VirtualDub.Open(<INAVI>,0,0);
VirtualDub.audio.SetSource(1);
VirtualDub.audio.SetMode(1);
VirtualDub.audio.SetInterleave(1,500,1,0,0);
VirtualDub.audio.SetClipMode(1,1);
VirtualDub.audio.SetConversion(48000,0,0,0,1);
VirtualDub.audio.SetVolume();
VirtualDub.audio.SetCompression();
VirtualDub.video.SetDepth(24,24);
VirtualDub.video.SetMode(3);
VirtualDub.video.SetFrameRate(0,1);
VirtualDub.video.SetIVTC(0,0,-1,0);
VirtualDub.video.SetRange(0,0);
VirtualDub.video.SetCompression(0x35327664,0,10000,0);
VirtualDub.video.filters.Clear();
VirtualDub.video.filters.Add("resize");
VirtualDub.video.filters.instance[0].Config(720,576,0);
VirtualDub.subset.Delete();
VirtualDub.SaveWAV(<OUTWAV>);
VirtualDub.audio.SetSource(0);
VirtualDub.audio.SetMode(0);
VirtualDub.SaveAVI(<OUTAVI>);
VirtualDub.Close();

2. For files that contains only video stream:

VirtualDub.Open(<INAVI>,0,0);
VirtualDub.audio.SetSource(0);
VirtualDub.audio.SetMode(0);
VirtualDub.audio.SetInterleave(1,500,1,0,0);
VirtualDub.audio.SetClipMode(1,1);
VirtualDub.audio.SetConversion(48000,0,0,0,1);
VirtualDub.audio.SetVolume();
VirtualDub.audio.SetCompression();
VirtualDub.video.SetDepth(24,24);
VirtualDub.video.SetMode(3);
VirtualDub.video.SetFrameRate(0,1);
VirtualDub.video.SetIVTC(0,0,-1,0);
VirtualDub.video.SetRange(0,0);
VirtualDub.video.SetCompression(0x35327664,0,10000,0);
VirtualDub.video.filters.Clear();
VirtualDub.video.filters.Add("resize");
VirtualDub.video.filters.instance[0].Config(720,576,0);
VirtualDub.subset.Delete();
VirtualDub.SaveAVI(<OUTAVI>);
VirtualDub.Close();