Hi Jay,
I currently use PowerPoint for slides, Audacity for recording and editing narration, a Yeti Blue (non-pro) desktop mic with pop-screen, and Premiere elements for assembling the slides (PowerPoint can spit out each slide as an image) and narration into a video.
Think I made a mistake in it though because I recommended stereo recording. You actually want to do narration in mono because stereo narration sounds weird, especially if the listener is using headphones, so be sure to set your mic and recording software for mono.
I also now pre-script most of my videos because it results in better narration.
Good luck!
--Brian