Recently released by privacy firm the Ponemon Institute, the survey also showed that most people download free software on the internet, such as music players and screen savers - software that often comes with adware and sometimes spyware, researchers said.
At the same time, most users do not want potential anti-spyware laws to prevent them from obtaining free software, the survey indicated.
Most of the 1,944 respondents did not have a clear understanding of the differences between adware and spyware. Forty-two percent said they had no idea how spyware ended up on their system. Most said they do not read end-user licensing agreements (EULA), describing them as too complex and confusing.
The web-based survey was sponsored by the Unisys Security Leadership Institute.
In other world news, Australia is leading the fight against malware by introducing tough new anti-spyware laws. The bill, if passed, will bring fines of up to $10,000 per incident.