On February 23, 2002, at 1015 central standard time, a Cessna 172S, N26105, contacted a runway marker sign following a loss of directional control while landing on runway 14 (3,600 feet by 75 feet, asphalt) at the New Holstein Municipal Airport, New Holstein, Wisconsin. The private pilot was not injured. The airplane was substantially damaged. The 14 CFR Part 91 personal flight was operating in visual meteorological conditions without a flight plan. The flight originated at Sheboygan, Wisconsin, at 0945. The pilot reported that after taking off at Sheboygan, he stayed in the traffic pattern and performed two touch and go landings. He then proceeded to New Holstein. He reported that he made his landing approach to runway 14 with the winds from 190 degrees at 15 knots gusting to 19 knots. The pilot reported that during the landing flare, the airplane floated so he added power to regain control. He reported the airplane touched down again, at which time the right wing came up and the airplane turned approximately 20 - 30 degrees to the left. He reported the airplane traveled off the left side of the runway toward a runway marker sign. The pilot reported he added power but was unable to clear the sign. The airplane contacted the sign and continued to travel approximately 400 feet prior to coming to rest. Inspection of the airplane revealed substantial damage to the firewall and lower fuselage structure.