A federal judge ruled Thursday that Korey Stringer's widow can proceed with her negligence lawsuit against the NFL and equipment maker Riddell Inc. over his heatstroke death. Kelci Stringer sued the league and Riddell following her husband's death in 2001, claiming the NFL hadn't done enough to insure that equipment used by players protected them from injuries or deaths caused by heat-related illnesses. Korey Stringer, a 335-pound lineman for the Minnesota Vikings, died from heatstroke after he practiced in the sweltering heat and humidity that pushed his body temperature to 108.8 degrees. He was 27.