Flash 4 and 5 provided the tools that allowed the Flash Player to receive and post data to a server called the Load Variables method. With Flash MX the Load Variables method is being replaced with LoadVars. This is a more efficient method of pulling and receiving server-generated information.
While you are working with the LoadVars method, you will see that it is similar to Flash 5's XML Object Methods. This is intentional, as the manner that XML Object parses data is more efficient and in line with ECMA-Script, the standard upon which ActionScript is based.
If you are working with XML, you will undoubtedly run into the problems of XML in Flash 5. Too much XML and the movie dies. Well, fans, this has been addressed. Flash XML is much smoother and more efficient. It still lacks a few "nice to have" features, such as support for SOAP, but it is significantly better than the first attempt.
Over the next couple of months you will see and hear a great deal from Macromedia about server side Flash control, which replaced Macromedia Generator. Now Flash can talk directly to the server and have ActionScript executed on the server. This is known as Flash Remoting. The potential for this is to allow Flash movies to be rich, thin clients in a web browser that can have persistent connection with your database. Great for building company applications.