Silverlight Question

[CraigPerreault]

I have this XAML code:

            <ListBox x:Name="SearchResultsList"  Height="260" Width="394" >
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <Grid x:Name="grdSearch">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition x:Name="Col0" Width="170"></ColumnDefinition>
                                <ColumnDefinition x:Name="Col1" Width="70"></ColumnDefinition>
                            </Grid.ColumnDefinitions>
                            <TextBlock Text="{Binding Name}" Margin="6,1,0,0" Grid.Column="0"/>
                            <TextBlock Text="{Binding Type}" Margin="6,1,0,0" Grid.Column="1"/>
                        </Grid>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>

I can change the size of the List Box like this

this.SearchResultsList.Width = 400

Can anyone show me how to change the width of Col1.  This does not work?
this.Col1 = new GridLength(200, GridUnitType.Pixel);

[JenniferNery]

Instead of setting width on each of your column definition, use "Auto", so each column can adjust its width depending on the size of its content. Also, set the HorizontalContentAlignment of ListBox to "Stretch", so that the grid would stretch as the ListBox increase its width.