music
Re: music
If you use the menu option "Insert -> Videos and sounds", then the change from music to videoclip is done automatically. Suppose you added a music clip to the first slide. If you add a video clip to the 4th slide, the music will automatically stop playing when the video begins to play. I have just tested it with Powerpoint 2000 and it worked fine, it should also work in newer versions.
To insert music to just one slide and go back to silence in the next (without adding a videoclip), you can do the following: in the next slide, add a recorded sound of 1 second of silence (use the Powerpoint built-in recorder); this will be enough to stop the music from the previous slide.
To insert music to just one slide and go back to silence in the next (without adding a videoclip), you can do the following: in the next slide, add a recorded sound of 1 second of silence (use the Powerpoint built-in recorder); this will be enough to stop the music from the previous slide.