I installed the subtitles support and enabled it, along with extra codecs, but neither Media player or Kmplayer will display subs. I then downloaded mplayer and from the command line used mplayer -sub movie.srt movie.avi
and it worked. I now have subtitles and just have to sort out the difference in aspect ratio to get a perfect result. Still very acceptable, though. I don't know whether mplayer would have worked on its own, but I'll stick with what I have.