I am very interested in developing RIAs. So I just wanted to know you opinions of each of them. I have a good foundation of XHTML and CSS, so is AJAX better?

-How compatible are they?
-How well do they handle images and animations?
-How flexible and versatile are they?
-Integration with the web/HTML/XML.
-Learning curve.
-Pros and Cons.
-Advices?

BTW, what's the difference between Jscript and Javascript?

Thanks for your replies.