While Americans are more concerned about personal information being stolen or misused through computer networks, many have not altered their online activity, according to a national study conducted recently by the Information Technology Association of America and Tumbleweed Communications, a provider of content-management solutions. The study revealed that late last year more than 70 percent of Americans were concerned about Internet and computer security as a result of the Sept. 11 attacks. Seventy-eight percent of respondents said they were either "very" or "somewhat" concerned that personal information, such as social security information, veteran health-care records and welfare information, could be misused. But despite those fears, respondents hadn't made major changes in their online behavior, states the survey. While only 7 percent of respondents said they use the Internet "a lot less" since Sept. 11, 34 percent said their usage has stayed the same. Meanwhile, 5 percent said they are using the Internet "a lot more" for news updates and information.