Disabling button on Validation error

I have couple of textboxes with custom validators:
(I don't mind if "wrong" data is sent back to object (the property is string), I just need to prevent the functionality of a button if there is an error, so if the binding is not the right place for that kind of validation please tell. I just like the Validation.ErrorTemplate support that i can use)

<ControlTemplate x:Key="validator" >
    <DockPanel LastChildFill="True">
       <TextBlock DockPanel.Dock="Right" Foreground="Red" FontSize="12pt">!</TextBlock>
       <Border BorderBrush="Red" BorderThickness="1.0">
            <AdornedElementPlaceholder />
       </Border>
    </DockPanel>
</ControlTemplate>

<TextBox Height="23" Width="150"  TextWrapping="Wrap"
         Validation.ErrorTemplate="{StaticResource validator}">
         <TextBox.Text>
            <Binding Path="StringProperty" UpdateSourceTrigger="LostFocus">
               <Binding.ValidationRules>
                   <local:NumbersOnly/>
               </Binding.ValidationRules>
            </Binding>
        </TextBox.Text>
</TextBox>

How can I disable specific button if any of the validation error is raised?

<Button Content="DO Work"  Height="57" HorizontalAlignment="Left"  Name="button1" VerticalAlignment="Top" Width="234" Click="button1_Click" />