I have an AVI file which I successfully converted from flv format to avi/mpg format using avs Video Converter (v.6) [trial version].

I can play that file with Windows Media Player (v.11).

I want to rip the sound track from the avi/mpg file using VirtualDub 1.7.8 (Build 28346). But I cannot get VirtualDub to open the file. The error message is:
"Can't locate decompressor for format 'xvid' (unknown). VirtualDub requires a Video for Windows (Vfw) compatible codec to decompress video. DirectShow codecs such as those used by Windows Media Player, are not suitable."

I downloaded and installed a XVID codec (that I downloaded from http://www.xvidmovies.com/codec/), and VirtualDub still gives me that error message, and refuses to open my files (I tried avi, and I tried mpg - same error encountered).

Need help on the following:
(a) What have I done wrong ?
(b) Is the codec a right one ?
(c) Is there any special 'place' (folder, etc) inside Windows XP (Home SP2) that I should put my codec so that it can be shared by other programs ?
(d) How can I get VirtualDub to open that avi/mpg file.