Don't be too quick to dump your plugin or applet based portions of your application. While ajax and dhtml can do drag and drop and other advanced user interfaces there still limitations especially when it comes to browser support. Plugins and applets have been around for a while and have been able to make ajax like requests for years. Applets provide a great set of ui components and apis that provide developers literally anything.
What is ajax method?
Do we have to use http get/post for the ajax calls?
Does ajax have the same meaning as xmlhttprequest?
Which are the knowledge requirements for personal ajax functionality?
What is the purpose of xmlhttprequest?
What do I need to know to create my own ajax functionality?
What is the disadvantage of ajax?
What are the real web applications of ajax currently running in the market?
What is advantage of ajax?
What does the dynamicpopulateextender control do? : asp.net ajax
Is it true that a xmlhttprequest objects belongs to the w3c standard?
Why did ajax kill himself?
What parts of the html_ajax api are stable?
How can javascript be debugged?