try this... from http://blogs.microsoft.co.il/blogs/tomershamam/archive/2007/12/16/wpf-listview-vertical-lines-horizontal-as-bonus.aspx
<ScrollContentPresenter x:Name="PART_ScrollContentPresenter"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
ContentTemplate="{TemplateBinding ContentTemplate}"
KeyboardNavigation.DirectionalNavigation="Local"
CanContentScroll="{TemplateBinding CanContentScroll}">
<ScrollContentPresenter.Content>
<Grid>
<!-- Container of vertical and horizontal lines -->
<ItemsControl Margin="3,0,0,0"
ItemsSource="{Binding Path=TemplatedParent.View.Columns,
RelativeSource={RelativeSource TemplatedParent}}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Border Width="{Binding Path=ActualWidth}"
BorderThickness="0,0,1,0"
BorderBrush="{DynamicResource verticalLineColor}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<!-- Fill background with horizontal lines -->
<ItemsControl.Background>
<VisualBrush TileMode="Tile"
Stretch="None"
Viewport="{Binding Source={StaticResource columnHeight},
Converter={StaticResource columnViewportConverter}}"
ViewportUnits="Absolute">
<VisualBrush.Visual>
<StackPanel HorizontalAlignment="Stretch"
VerticalAlignment="Stretch">
<!-- Add Rectangles here for more horizontal lines -->
<Rectangle Height="{DynamicResource columnHeight}"
VerticalAlignment="Stretch"
Fill="{DynamicResource horizontalLineColor1}"
Width="1" />
<Rectangle Height="{DynamicResource columnHeight}"
VerticalAlignment="Stretch"
Fill="{DynamicResource horizontalLineColor2}"
Width="1" />
</StackPanel>
</VisualBrush.Visual>
</VisualBrush>
</ItemsControl.Background>
</ItemsControl>
<ContentControl Content="{TemplateBinding Content}" />
</Grid>
</ScrollContentPresenter.Content>
</ScrollContentPresenter>