Movie Maker

I have created a slideshow in Movie Maker. I wanted to free up some disk
space so I moved the picture files to my Passport hard drive. When I move
these files from my c drive, those pictures no longer appear in the slideshow
that I created....just black frames. Have I not saved the movie file
correctly or do I have to keep the pictures that I used in the slideshow in
the original location they were in when the slideshow was created? I have
made dvds of the slideshow, but would like to be able to go in and edit in
the future, but also need to free this disk space from my c drive.

Thanks for any help.