I recently removed terminal services from my test server as I was through with it and the evaluation license was about to run out. When I tried to connect to my headless server using remote desktop I found that it was disabled by the removal of ts.
Thanks to a blog by cogent free knowledge I was able to enable remote desktop remotely.
Using regedt32, connect to the remote machines registry and change the following key from 1 (disabled) to 0 (enabled):
No need to reboot, it works straight away.