iPhoto: FIT YOUR SLIDE SHOW TO THE LENGTH OF YOUR MUSIC

If you don't want the music to loop during your slide show, you can make the slide show adjust to the length of the music; that way it's not as annoying listening to the same song over and over again. So, select the album you want to use as your slide show from the Source list, and then click the Slideshow button at the bottom of the iPhoto window. When the slide show options appear, click on the Settings button, and in the resulting dialog, turn on the option to Fit Slideshow to Music and click OK. Once you click Play, iPhoto will adjust your slides' duration time so that each image appears onscreen once as the song plays, without the annoying "loop" factor.