Although most versions of Windows operating system such as Windows 2000, 2003, 2008, XP and Vista do come packaged with Remote Desktop, however it’s disabled by default. Turning on and enabling the Remote Desktop via local console is easy, where Microsoft provides similar GUI (graphical user interface) in all editions of Windows.

However, if an off-site server needs to be access via Remote Desktop Connection (RDC) client immediately, yet the Remote Desktop is not enabled on the server, then it will be a headache. Luckily it’s possible to remotely enable the Remote Desktop service on a remote PC or server by remotely editing its registry.

To remotely enable Remote Desktop on another computer, follow these steps:

1. Login to the workstation with administrator credentials.
2. Run Registry Editor (regedit).
3. Click on File menu.
4. Select the Connect Network Registry in the pull down menu.
5. A “Select Computer” dialog search box is opened. Type the host name of the remote computer in the text box, or browse Active Directory to locate the remote server, or click on “Advanced” button to search for the remote computer.
6. Click OK after the remote computer is selected. A node for the remote computer network registry will be displayed in the Registry Editor with HKEY_LOCAL_MACHINE (HKLM) and HKEY_USERS (HKU) hives.
7. Navigate to the following registry key for the remote computer:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server
8. In the right pane, locate a REG_DWORD value named fDenyTSConnection. Double-click on fDenyTSConnection and change the value data from 1 (Remote Desktop disabled) to 0 (Remote Desktop enabled).

That’s it.

Taken from here

Ozzik.