<data:DataGrid x:Name="dataGrid5" 
    Height="120" Width="450" Margin="0,5,0,10" >            
    <data:DataGrid.Columns>

        <data:DataGridTemplateColumn Header="Name">
            <data:DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal">
                        <TextBlock Padding="5,0,5,0"
                            Text="{Binding FirstName}"/>
                        <TextBlock Text="{Binding LastName}"/>
                    </StackPanel>
                </DataTemplate>
            </data:DataGridTemplateColumn.CellTemplate> 
            <data:DataGridTemplateColumn.CellEditingTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal">
                        <TextBox Padding="5,0,5,0"
                            Text="{Binding FirstName}"/>
                        <TextBox Text="{Binding LastName}"/>
                    </StackPanel>
                </DataTemplate>
            </data:DataGridTemplateColumn.CellEditingTemplate> 
        </data:DataGridTemplateColumn>              

        <data:DataGridTextColumn
            Header="Address" Width="300"
            DisplayMemberBinding="{Binding Address}" />

    </data:DataGrid.Columns>
</data:DataGrid>