Purpose: mDNSResponder.exe is a file used by the Apple Bonjour Networking service. According to Apple:
"Bonjour, also known as zero-configuration networking, enables automatic discovery of computers, devices, and services on IP networks. Bonjour uses industry standard IP protocols to allow devices to automatically discover each other without the need to enter IP addresses or configure DNS servers. "

Gizmo Project (http://www.gizmoproject.com) adds Bonjour Service to the Windows XP (or Windows 2000, or Windows NT) Services folder.
This service starts automatically and runs a process named mDNSResponder.exe which cannot be ended by Windows Task Manager.
To remove, it must first be disabled in Services. mDNSResponder.exe is essentially the "driver" for this networking service.

Apple is the developer of the Bonjour Networking.
SIPphone, Inc. [www.sipphone.com] is the developer of the Gizmo Project software and service.

Bonjour allows applications like iTunes and Safari to advertise and discover services on the local network. Having Bonjour running enables you to connect to hardware devices like Apple TV and software services like iTunes sharing and AirTunes. If you disable Bonjour, any network service that explicitly depends on it will fail to start.

mdnsresponder.exe uses excessive system and memory resources with no corresponding benefit. Applications such as these should be disabled to improve overall system performance.

Percentage of recently scanned PC's with this process running: 5.05%
Average CPU use for this program: 0%
Average RAM for this program: 3 MB