Seventy-four percent of office workers use their work computer for personal tasks, the survey of nearly 530 Information Technology (IT) managers and end users at companies in North America, Britain and Europe found.
Fifteen percent do not use their work computers for personal purposes while 11 percent of the respondents preferred not to answer the question.
The survey was conducted September 17-31 by NewDiligence, an independent market research firm, for Belmont, California-based FaceTime Communications, a provider of Internet security solutions.
The survey looked at publicly traded and privately held firms, non-profits, government organizations and educational institutions. The margin of error was not published.
The most frequent personal use of a work PC was to send email to friends and family, followed by looking at Web sites (84 percent), banking and personal finance (68 percent) and shopping on the Web (57 percent), the survey found.
Fifty-seven percent use their work computer to listen to music or look at pictures and video while 44 percent use it for Instant Messaging (IM) chat with friends and family.
Thirty-two percent connect with friends through social network sites from their work computer and 20 percent update their social network profiles with photos and videos while at work.
Eight percent use their work computer to update their personal blog or comment on other blogs.
But if employees are using their work computers for personal activities they're also using their home computers for work, according to the study.
It found that 90 percent of employees own a PC and 85 percent use it for work reasons.
These include email (85 percent), loading documents brought home on a disc or flash drive (79 percent), or downloading documents from the corporate network (73 percent).
The survey also found that visits to social network sites while at work were not strictly personal.
Fifty-one percent of end users access social network or media sites such as Facebook, MySpace, LinkedIn or YouTube at least once a day and 79 percent do so for business reasons - professional networking, research or learning about colleagues.