Which audio tracks are necessary for backup?

[The Shade]

I don't know if this has been answered before - if so I'm sorry for the repost - but I was unable to find it while searching.

I typically use DVDShrink - and I had a question about the different audio tracks, specifically the ones associated with the movie.

I will typically see a listing of several audio trakts. It might look something like this:

1. AC3 5.1-ch English 450 MB
2. AC3 2-ch English 190 MB
3. AC3 2-ch English 190 MB
4. AC3 2-ch French 189 MB
5. AC3 2-ch - Director's Comment 170 MB
6. AC3 2-ch - Director's Comment 170 MB


What are all these for? I leave the 5.1-ch --- but always remove any audio that is non-English. But what about the other ones? Are they important? I would love to be able to remove them as well, to give more space to the movies, but don't want to delete something important.

Plus, it looks like some of them are the same (like the 2 Director's Comments or the two 2-Ch English.)

If I just keep the 5.1-ch audio, am I losing anything, or losing an ability to hear the movie if not played on certain equipment? What's the rule of thumb?

Thanks all for your help.

[MOVIEGEEK]

Use PowerDVD or WinDVD to listen to the tracks,the order they're in is the same as in DVDShrink.I wish DVDShrink would allow us to listen to all tracks...maybe in a future release.
DTS audio sounds the best but only 40% of standalones have an onboard decoder.If you don't have a 5.1 system and will never have one I would use 2ch AC3 because1)it's louder(2)it's smaller(3)it works on all DVD players.