Why use Flash instead of static HTML?
- If you have sophisticated animation.
- If you have user interface elements that you can't replicate in HTML.
- If you want to protect content from right click>download.
Why use PHP instead of static HTML?
- If you want to pass information from one page to another.
- If you want to create a persistent state across pages.
- If you want to use data from a database.
- If you want to use a templating system to reduce repetition.