System.Management.SelectQuery query = new System.Management.SelectQuery("Win32_VideoController");
            System.Management.ManagementObjectSearcher searcher = new System.Management.ManagementObjectSearcher(query);
            foreach (System.Management.ManagementObject ManageObject in searcher.Get())
            {
                String ResX = ManageObject["CurrentHorizontalResolution"].ToString();
                String ResY = ManageObject["CurrentVerticalResolution"].ToString();
                resolutionLabel.Text = "Resolution: " + ResX + " x " + ResY;
            }

int deskHeight = Screen.PrimaryScreen.Bounds.Height;
int deskWidth = Screen.PrimaryScreen.Bounds.Width;

public string GetScreenResolution()
{
        int width = Screen.Width / Screen.TwipsPerPixelX;
        int height = Screen.Height / Screen.TwipsPerPixelY;
        return "Screen Resolution is " + width + " x " + height;
}

/// <summary>
/// Gets the current screen resolution
/// </summary>
/// <returns>Screen resolution as Size</returns>
privatestring GetScreenRes()
{
    int iWidth  = Screen.PrimaryScreen.Bounds.Width;
    int iheight = Screen.PrimaryScreen.Bounds.Height;

    return "Resolution is " +  iWidth + " x " +  iheight;

}