Most but not all computer servers are going to the command line I.e no graphics. Even as I understand it, MSWindows 8 server is going to the command line. Never hurts to have a back up monitor for an emergency, for portability, or if you just want to go retro.
Also see: http://www.instructables.com/id/Extra-TV-setup/
Note: Tried two old portable B&W tv's and it did not work.
Update: Using the dvd player as a monitor for Raspbmc!
Step 1: Computer video output.
Step 2: Adapter cables and adapters.
Note: The Comodore 1701 and related monitors supported the chroma and luma inputs. No connection to Cyber Technology.
Step 3: Make your own adapter.
Note: Have not tried this myself yet.