XAML vs XUL vs MXML Comparision

MXML
Runs anywhere Flash Player 7
Server required
Uses ActionScript 2.0
XPath support: no
CSS support: limited

XAML
runs Runs only on Longhorn
Server not required
Uses .NET languages
XPath support: yes
CSS support: no

XUL
Runs on any platform.
Server Not Required
Javascript, Python, C++
XPath support: yes
CSS Support: excellent.