Need advice on editing programs for a project

I have a project that I have been wanting to work on for some time, and could use some advice.  I like the TV series Roswell, but do not like how the music was changed on the dvd's. I have copies of the episodes with original audio, and would like to mux them with the video from the dvd.  What program would be the easiest, or best to do this and re sync the audio.  Please keep in mind I will likely have to do it in sections as the original audio versions are different lengths due to commercial breaks.  Any info or feedback would be appreciated.

I have been playing with videos for years. I know how to rip, convert from NTSC to PAL, how to author dvd's.  I do have some problems with the pitch adjust from PAL back to NTSC as the voices sound a little high pitched.  Never found the best way to adjust the pitch without adjusting the running time.  I have used or tried many programs out there, TMPGenc Xpress for example.  I would like to find a program where I can try to sync it, and hopefully have a preview option.  If it previewed in real time that would make it easier.  But I havent used many actual editing programs.