Software inspection is an effective way to assess product quality and to reduce the number of defects. In a software inspection the inspection meeting is a key activity to agree on collated defects, to eliminate false positives, and to disseminate knowledge among the team members. However, inspection meetings often require high effort and may lose defects found in earlier inspection steps due to ineffective meeting techniques. Only few tools are available for this task. We have thus been developing a set of groupware tools to lower the effort of inspection meetings and to increase their efficiency. We conducted an experiment in an academic environment with 37 subjects to empirically investigate the effect of groupware tool support for inspection meetings. The main findings of the experiment are that tool support considerably lowered the meeting effort, supported inspectors in identifying false positives, and reduced the number of true defects lost.