Hi moress and I second SJ's welcome to cdfreaks,
I've never tried to do this, but it doesn't look too bad and looks as though it can be accomplished with freeware.
Check out this link:
[Add permanent subtitles to S/VCD,DVD,AVI with ffdshow/vobsub](http://forum.videohelp.com/viewtopic.php?
Let us know how the project goes.
Hope this helps...