when subtitles are in idx/sub format you need VobSub to view them available here
http://www.filemirrors.com/search.sr...obSub_2.23.exe
once it's installed as long as the avi idx and sub have the same file name, vobsub should start automatically. to select the langauge on multilanguage subs look for the green arrow in the system tray and select it form there.