I had to do this just a few minutes ago and I figured I should probably post it here.

1. Open Registry Editor by going to Start -> Run and typing in regedit.
2. Go to File -> Connect Network Registry… and type in the name of the computer where you want Remote Desktop enabled. Click OK.
3. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server of that computer.
4. Double-click the DWORD called fDenyTSConnections and set its value to 0. Click OK.

That’s it! Remote Desktop is now enabled!