Open source tools for creating eLearning & Flash Presentations?

I came across an interesting suite of tools on www.articulate.com—that let you create interactive and sophisticated elearning presentations and quizzes out of PPTs.

While these are very powerful tools, our requirements is not as demanding and we need to do only a handful of elearning courses as a one-off activity. Purchasing such a professional suite would be an overkill. We would like to do it ourselves with any simple tools that may be available.

Are there any open source tools available that can help us with this?

- Slides with synchronized audio & navigation
– Simple Assessments at the end of the course
– Publishable as a set of HTML and Flash files
Nice to have:
– Animations & annotations
– Screen captures
– Transcripts
– Embedded video

Thanks!