DataGridView checkboxes

I've tried for about an hour now just to figure out if a checkbox in a DataGridView control is checked or not. The Value field is always null, whether checked or not, and there is no Checked field like a Checkbox has. How can I detect if a cell is checked or not?

private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
      // Column 0 is the Checkbox column that I need.
      if (e.ColumnIndex == 0)
      {
           // This gets the Checkbox cell.
           DataGridViewCheckBoxCell cell = (DataGridViewCheckBoxCell)fileGrid.Rows[e.RowIndex].Cells[0];

           // Always displays True.
           MessageBox.Show((cell.Value == null) + "");
      }
}