private void button1_Click(object sender, EventArgs e)  
{  
  if (checkAdobeReader() == true)  
  {  
    MessageBox.Show("有安裝 Adobe Reader ");  
  }  
  else 
  {  
    MessageBox.Show("沒有安裝 Adobe Reader ");  
  }  
}  
/// <summary>  
/// 確認是否有安裝 Adobe Reader  
/// </summary>  
/// <returns>true: 有安裝, false:沒有安裝</returns>  
private bool checkAdobeReader()  
{  
  Microsoft.Win32.RegistryKey uninstallNode = Microsoft.Win32.Registry.LocalMachine.OpenSubKey(@"SOFTWARE/Microsoft/Windows/CurrentVersion/Uninstall");  
  foreach (string subKeyName in uninstallNode.GetSubKeyNames())  
  {  
    Microsoft.Win32.RegistryKey subKey = uninstallNode.OpenSubKey(subKeyName);  
    object displayName = subKey.GetValue("DisplayName");  
    if (displayName != null)  
    {  
      if (displayName.ToString().Contains("Adobe Reader"))  
      {  
        return true;  
        // MessageBox.Show(displayName.ToString());  
      }  
    }  
  }  
  return false;  
}