Change default audio in .VOB or .MPG files

[dsmith1984uk]

I watch television through my PS3, I got fed up constantly changing CD's everytime I wanted to watch a movie so I built a MediaServer.
I wanted to store all my DVD's on the mediaserver especially things like LOST series. Then I can just select play all and sit back and relax.

Here's the problem a lost disc will start with 2 folders Audio_TS and Video_TS, inside are .VOB files.
I've been copying all these .VOB files out deleting the ones which aren't a scene and renaming them as .mpg files so they will play back on the PS3.
Now 90% of them are perfect but there are some wierd things happening.

For example one of the .VOB files played back in japanese on the PC, I renamed it to .MPG and it now plays english on the PC but load it up on the PS3 and it's Japanese.
In Season 3 disk 3 and 4 are both in foreign, on the PC I can select english but on the PS3 I do not have this option.
There are different language problems on other disks but I'm not about to go through them all.

I guess my question is how do I change the default audio?
These .VOB files certainly have English in them but for some strange reason it isn't always the default.
I'd ideally like to remove all other languages and commentary so it had no choice but to always use English.

[hech54]

I don't see any other option other than making your preferred language the ONLY language....and that is done easily by re-authoring the DVD.