KEYDOWN EVENT in silverlight shows dX or NumPadX instead of numbers

Question

I tried the following in Silverlight 3.0 and browsed in Mozilla firefox 3.5

//code to display the key down
private void comboBox1_KeyDown(object sender, KeyEventArgs e)
        {
            button1.Content = e.Key.ToString();
        }

When number keys are pressed, I get a response like D1, D2.....

When numpad keys are pressed, I get a response like NumPad1,NumPad2 .....

I would like to know

1) why numbers are not displayed as such

2) why there is a differentiation between numpad and nonnumpad key press