DisplayPort adapters are available in either Active or Passive types. The NVidia GeForce cards that we currently use do not need a particular type to utilise three or four outputs. If you have a system that use a Radeon video card, using an active adapter will permit you to use three simultaneous outputs, while a passive adapter will usually limit you to two.
DisplayPort to DVI: StarTech DP2DVIS
DisplayPort to VGA: StarTech DP2VGA2
DisplayPort to HDMI: StarTech DP2HDS