Disable Ctrl+Alt+Del, Ctrl+Tab, Alt+F4 in Windows Vista

Hi everyone. I'm working on an application, and I need to be able to disable Ctrl+Alt+Del in XP and Vista. My code accesses the registry in order to do so. It works in XP, but doesn't work in Vista. Below please find the code I'm using.

RegistryKey regKey;
                    string keyValueInt = "1";
                    string subKey = "Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System";
                    try
                    {
                        regKey = Registry.CurrentUser.CreateSubKey(subKey);
                        regKey.SetValue("DisableTaskMgr", keyValueInt);
                        regKey.Close();
                    }
                    catch (Exception ex)
                    {
                        //MessageBox.Show(ex.ToString());
                        CustomMessageBox message = new CustomMessageBox(ex.ToString(), false);
                        if (DialogResult.OK == message.ShowDialog()) { }
                        message.Dispose();
                    }

Ontop of that, I also have to be able to disable Ctrl+Tab and Alt+F4 in both XP and Vista. Does anyone have any ideas? Thanks.