Windows Audio Endpoint Builder
Windows Vista Service Details
Endpoint devices are things like speakers, microphones, etc. I have this strange feeling this has been broken out of the 'Windows Audio' service where it used to lie, to include much of the new DRM crazyiness that you read about in Vista. Securing down your computer so that certain audio devices, if not secure (i.e. analog) get different quality audio than secure channels. I cannot confirm that this is the culprit, as honestly, I havn't seen any of these 'nasty' things that MS put into Windows (but most likely had to, to allow for a secure channel for decoding DRM whatnot). Anyway, on the surface, it tells allows Windows to more effectively manage your audio hardware. It knows how many mics, speakers, etc you have, rahter than just sending information out blindly.
Manages audio devices for the Windows Audio service. If this service is stopped, audio devices and effects will not function properly.
Consequences of Stopping:
If Disabled, Windows Audio service wont be able to start
All services listed in 'Required For' will be unable to function