Pre-order your copy of the sequel to Actionscript: The Definitive Guide by Colin Moock, now updated to cover everything new in Flash MX Actionscript, bound to be one of the best 50 dollars you will spend for the next year or so. Read a sample chapter, Chapter 10 - Events and Event Handling as apart of a new article on the Macromedia Designer & Developer Center, should give you a good feel for the contents of the book.