After polling 2,400 U.S. Internet users, researchers found online revenues, which grew from $7.4 billion in the third quarter of 2000 to $34.7 billion in the third quarter of 2007, increased far faster than positive attitudes about shopping online.

Especially among low-income groups who use the Internet, caution about revealing personal information and credit card numbers online remain, researchers said.

"Their concerns about their financial safety online make them reluctant to make full use of e-shopping," the report said.

While online revenues increased fivefold, those who said they shopped online more than doubled, from 22 to 49 percent.

What holds people back is confusion and caution, the report said. Three-quarters of those polled said they did not like divulging personal information online. And 58 percent said that online shopping was frustrating, confusing or overwhelming.

Online banking increased -- from 27 percent in 2005 to 39 percent in 2007 -- and a vast majority (93 percent) have done "something related to e-commerce," researchers said, including research, booking reservations and bidding at an e-auction.