Why don't you download a utility called avicodec(freeware). What it does is indicate what the FourCC of your file is(i.e what codec the avi uses). Normally I don't install a whole codec pack just because my system does not have a single codec. Once you know the codec of your avi(the utility also indicates whether your system has the codec installed). If you don't have the codec, google for it using the FourCC indicated by AviCodec and then install it(if it does not have an installable i.e. exe then Click Run and type regsvr32 ....dll[the codec file]). Then you should have no problem converting to any format using any program and playing the file too should be easy.
Hope this helps.