Subtitles in MKV file

[maass]

hi,
i converted an .avi to .mkv using Xvid4PSP
i wanted subtiltes into the mkv.
i used the option Subtitles -> ADD,but the subtitles i add are being hardcoded to the video.
some of the .mkv files i see are like they have subtitles,but they are addable and removable.
how can i save subtitles such in an .mkv.

thanks

[Baldrick]

Convert using xvid4psp(if you are not doing any shrinking or resizing you might be able to remux to mkv directly without any conversion also) and then use mkvmerge to add the subtitles to the mkv.

[maass]

Thank you very much Baldrick....that worked