Sizing the content to fit into screen resolution

If you want to scale really everything including font sizes, you could probably apply a scale transform to your content, and bind it's X and Y values to the window's width and height. You would then also need a value converter to convert those to the appropriate scale.

If you want to scale everything to the size of the window just put everything inside a Viewbox control.

Viewbox is quite useful if you need the content of your window to scale proportionally when you resize the window (for example maximize it). In this minimalistic page

<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
    <Viewbox>
        <StackPanel>
            <TextBlock FontSize="14">Example</TextBlock>
            <Border Background="Aqua" Width="100" Height="100"></Border>                    
        </StackPanel>
    </Viewbox>
</Window>

you have a TextBlock and a colored Border stacked vertically; if you start this xaml the window will have a size of 300x300, the font of the TextBlock will be 14 in size and the colored border will be 100x100. If you rescale the window you will see both the TextBlock and the Border scale accordingly (so they'll be no more of the size you've specified in the xaml), keeping relative proportions. Viewbox is really useful, in this respect, if you need a window whose internal components layout look always the same independently from the final resolution it will be displayed (what does matter is aspect-ratio, thought). This obviously work with any contents you'll put inside the Viewbox (we had an application with videos and 3D views for example). Note that in Visual Studio 2008 you'll not be able to see the content of the Viewbox in the Designer.

Hope this help.