Vista had come with new and cool look & feel. If you want to add the Vista Aero style theme to you WPF application running on Window XP then it is very easy trick. You don’t need any third party library or tool to achieve this.
To do this all you need to do is to add following lines of xaml code into the designer of your window right after window tag:
<ResourceDictionary Source="/PresentationFramework.Aero, Version=126.96.36.199, Culture=neutral, PublicKeyToken=31bf3856ad364e35, ProcessorArchitecture=MSIL;component/themes/aero.normalcolor.xaml" />
If you want to apply this look through out the application then add this to app.xaml under <Application.Resources> section.
The limitation of this technique is that it don't change the look of container form. You can see it still looks like a normal XP form.