Shopping online with credit cards: We love it. We fear it.

Americans love the convenience of shopping online, but many still get a twinge of nervousness when typing that credit card number into the computer, and those who have the least harbor the most fear.

That's the major finding of research released this month by the Pew Internet & American Life Project.

Americans have largely gotten over their initial resistance to using their credit cards online, with 66 percent of those who have online access saying they have purchased a product online. But ambivalence remains: Three out of four Internet users either agree or strongly agree that they don't like giving out their card numbers or personal information online.

"Our analysis suggests that if concerns about the safety of the online shopping environment were eased and if shoppers felt that online shopping saved them time and was convenient, the number of online shoppers would be higher," concludes John Horrigan, associate director at the nonprofit research firm.

There are billions of dollars at stake in easing those doubts. If retailers and the card industry can allay the lingering fears -- something that the steady drumbeat of identity theft reports makes unlikely soon -- the number of Americans willing to shop online would rise from 66 to 73 percent, the study estimates. The amount of money spent online, which stood at $34.7 billion in the third quarter of 2007, would rise accordingly.

Gender and race have little to do with people's attitudes toward shopping online, but income is a very large factor.

If you compare people in households with less than $25,000 in income and compare them to those in households with annual incomes of $100,000 or more, those with less are far more nervous about using credit cards, and far less likely to describe the online shopping experience as convenient.

Here are the numbers