Dear bmains,
What you need to run flash depends what you are using it for.
IF for animation, purchase Flash MX 2004 and get started.
for development,(I suspect You are one :-)
purchase Flash Mx2004 Professional.
If you want to create 3 tier applications, u need a web server like apache/ Win IIS installed and configured to run ASP or PHP or a server side Lang of your choice.
Furthermore, You also have a choice of using Flash Remoting for client-server interaction.that of cource requires you to install the remoting environment.
As you mentioned that you are a beginner, it would be wise to start learning with the right perspective.
Hope this helps :-)
vikas/alakh
[email protected]