AJAX Frameworks?

[mh10190]

Im starting to experiment with AJAX and more interactive web technologies.
And i came across 4 Framsworks (or tools) to help me.
Which would you use, and why?

http://www.rubyonrails.org/

http://atlas.asp.net/Default.aspx?tabid=47

http://code.google.com/webtoolkit/

http://wasp.sourceforge.net/content/?PHPSESSID=ddda79a2704dc8e856a78a56cacd1def

And if anyone knows, What is Windows Presentation Foundation?

ThanQ

[mostwanted]

Ruby On Rails isn't an AJAX framework.

[Houman]

I think one of the more popular ones is qooxdoo:
http://qooxdoo.org/

[Corvillus]

Ruby on Rails itself isn't an AJAX framework. However, Rails provides a nice Ruby based API for the script.acluo.us ( http://script.aculo.us/ ) and Prototype ( http://prototype.conio.net/ ) frameworks. However, both of them can be used seperately from Rails. Also, the Dojo Toolkit is another popular framework ( http://thedojo.net/ ).