On March 13, 1999, about 1255 Eastern Standard Time, a Socata TBM 700, N700SP, was substantially damaged during a landing at the Winchester Regional Airport, Winchester, Virginia. The certificated private pilot and passenger were not injured. Visual meteorological conditions prevailed for the flight that originated from Montreal Dorval International Airport, Montreal, Canada. An instrument flight rules flight plan was filed for the personal flight conducted under 14 CFR Part 91. The pilot stated that he landed the airplane with the landing gear retracted. He flew a downwind, base, and final leg for Runway 32. While in the traffic pattern, he was preoccupied with an airplane on an instrument approach, and an airplane that had just landed on the runway. The pilot was discussing the traffic with the passenger, and did not remember hearing an audible warning for the landing gear. However, he believed that the audible warning system was working properly. A local mechanic witnessed the landing. He stated that the airplane flew approximately 100 feet above the runway threshold, landed approximately 600 feet beyond the approach end, and slid approximately 1,400 feet. The airplane came to rest on the runway, to the right of the centerline. The flaps, propeller, and wings sustained damaged. After the accident, the mechanic approached the airplane and observed the gear lever in the "UP" position. The airplane was brought to a hanger and placed on a lift. The power was turned "ON" and the audible warning sounded immediately. The gear lever was then placed in the "DOWN" position. The gear extended, the three green gear lights illuminated, and the warning horn ceased. The mechanic further stated that four different events; stall, autopilot disengage, gear retracted while the flaps are extended, and radar altimeter alert, activate the same audible warning. The following is an excerpt from the TBM 700 Maintenance Manual: "buzzer LS7 (Altitude preselect indication) buzzer LS8 (Auto Pilot disconnect indication) buzzer LS6 (VMP warning)... LDG up and throttle reduced -------------------> high-pitch sound LDG up and flap down----------------------------> high-pitch sound Stall-----------------------------------------------------> low-pitch sound LDG up, throttle reduced and stall------------> alternate high-low pitch sounds LDG up, flaps down and stall-------------------> alternate high-low pitch sounds"