Just thought I’d add one thing – if you are stuck with using powerpoint at the clients request (I thought it was just me these days) version 2003 and up will also take an mpeg2 as embedded video. I use this method all the time (unfortunately).
Personally, if you can, I would take onboard the suggestion of using the provided slidepack as a storyboard and then provide something equal (or most likely better) yourself using Vegas only. Believe me, you don’t want to still be doing content for other peoples slidepacks in 3 years time. Show them what you can do, and what powerpoint CAN’T do.
Best of luck!