Narration and Powerpoint Show

I'm working on a slide project (60 slides) that I want to insert narration
for each slide. This is going to be a training cd that will be mailed out to
customers. My contact who is doing the sound narration wants to know the best
final product to get to me so I can insert into each slide.He was going to
get me the total narration of the entire ppt presentation on audio tape, but
I wanted to recommend to him to instead break up the entire narration into
individual slide size sound bites and save them as wav files for easy
insertion into the ppt file. I just want to know if anyone agrees with this
procedure or does someone have a better idea on doing this. (What other kind
of sound files can I insert into powerpoint slide show other than wav) Also,
if I was to get this as one long narration, what software can I use to
individually break it up into seperate sound bites myself? (free or $)