While connect to a remote computer using windows remote desktop, the normal CTRL+ALT+DELETE or simple Windows key will \
not effect the remote machine, only your local computer. So these shortcuts give you control on the remote computer.

Key combination Function Similar local keys 

CTRL+ALT+END                Opens the Windows Security dialog box
CTRL+ALT+BREAK              Toggles the Terminal Services client display from window to full screen
ALT+INSERT                  Cycles through running programs on the remote computer
ALT+HOME                    Displays the remote computer's Start menu
ALT+DELETE                  Displays the remote window's Control menu
CTRL+ALT+NUMBER PAD MINUS   Places an image of active window onto the TS clipboard
CTRL+ALT+NUMBER PAD PLUS    Places an image of the entire Terminal Services client on the Terminal Services clipboard

http://sqlblogcasts.com/blogs/simons/archive/2006/02/06/CTRL-ALT-DEL-in-Terminal-Services.aspx

Windows 7 Remote Desktop Server Disabled[-][--][++]

First off, make sure the Remote Desktop Services service is started.

In the Remote Desktop settings of my Windows 7 Professional 64bit install the Remote Assistance Allow Remote Assistance checkbox was available but the Remote Desktop 3 options of

  1. Don't allow connections from this computer
  2. Allow connections from computers running any version of Remote Desktop (less secure)
  3. Allow connections only from computers running Remote Desktop with Network Level Authentication (more secure)

were all greyed out.

I solved this by running gpedit.msc and navigating to Computer Configuration Right Administrative Templates Right Windows Components Right Remote Desktop Services Right Remote Desktop Session Host Right Connections and setting Allow users to connect remotely using Remote Desktop Services to 'Enabled'. Then when I went back into the regular Remote Desktop window, they were available, I then selected the 2nd (less secure) option.