A regular question from PPT 2k users is "what happened to the Music feature that was available in PPT 97?"
I think I've found something at:
http://www.shockwave.com/sw/content/grooveblender. If you download this shockwave app you can save the music files you create in wma format - which will insert into a PPT presentation.
There are 3 styles of music available: Funk, Hiphop and Electronic.

I'm off to play ....