Juggling a 60-hour workweek and long commutes to clients in the outlying suburbs, Sandy Hoffman, 52, a self-employed accountant in Arlington, has turned to the Internet for her Christmas shopping, to save time.

And she is doing some of it at work.

As she searches the World Wide Web for a company offering parachute lessons for her husband, she does the time-consuming browsing on her home computer.

But for speedy connections, she turns to the computers where she frequently works, at a medium-sized government contractor, where high-speed communications links help her connect faster.

"I'm time-conscious, not price-conscious," Hoffman said, adding that she always is careful to keep her online visits at her client's workplace short. "Five minutes there would take 15 minutes at home," she said.

Online sales during this holiday season are expected to reach $6 billion, and one of the peak shopping periods is in the middle of the day, when many buyers are presumably at work, analysts said.

Companies have noticed, too. A management backlash is brewing in workplaces across the country. More companies are clamping down in response to the growing ranks of workers buying Christmas gifts, trading stocks and checking NFL scores online during office hours. Unlike Hoffman, who said she keeps Web use to a minimum at work, other workers have shown they can't be trusted, employers say, straining corporate resources and hurting productivity.

"You get suspicious if a person is at a computer eight hours a day and they are not getting anything done," said Christa Carone, a spokeswoman for Xerox Corp., which has fired 40 workers for Internet abuse in the past year. "You start to say, 'What are they doing in there?' "

Xerox isn't alone in its concerns. In a survey conducted for The Washington Post last week by the American Management Association, about half of 900 companies reported they now monitor employees' Internet use, and another 12 percent said they intend to begin monitoring it.

This means that with one mouse click, an executive might be able to print out every Web site a worker has visited over the past month. If that list includes sexually explicit sites or too many trips to online booksellers' shelves, workers can find themselves with some explaining to do.

"Employees should know that equipment given to them for business purposes is not theirs and the company has a legitimate interest in making sure it's used for business purposes," said Eric Rolfe Greenberg, research director for the American Management. "Companies have a responsibility and every legal right to track what's done with their technology."

Companies such as Ameritech Corp. and grocer Giant Food Inc. are taking a hard-line approach, banning all personal Internet use in the workplace. About 11 percent of firms have dismissed employees for Internet abuse, according to the management association's survey.

At Xerox Corp., based in Stamford, Conn., the problems came to light when managers at different work sites across the country began raising productivity questions about workers putting in long hours without accomplishing much work. The 40 workers were fired after systems operators learned they were actually spending their time shopping, visiting sexually explicit sites or gambling, company officials said.

"This wasn't a case of somebody popping up one screen for a couple minutes," spokeswoman Carone said. "These were people who weren't able to get their work done because they were spending so much time cruising the Web."

Like Xerox, the Arlington technology firm CACI International Inc. took "swift and absolute action" against an employee who was downloading sexually explicit material during the day, a company spokeswoman said. Officials at Ameritech, a Chicago telecommunications firm, watch for abuses and "coach" employees who violate the rule.

"The policy is to focus on the customers, and that is what the customer expects," Ameritech spokesman David Pacholczyk said.

At Giant Food, based in Landover, employees who are issued computers are required to sign an agreement that they will not use the machines for personal purposes, including online shopping. "We're pretty rigid," spokesman Barry Scher said. "People know what they can and cannot do."

United Technologies Corp., a Hartford, Conn., maker of elevators and helicopters, has informed its employees that it monitors their Internet use, said Pat Gnazzo, the company's vice president of business practices. It also expects employees to snitch on colleagues who misuse their computers.

The crackdowns apparently are altering many employees' behavior. Braeden Trotman, 25, a sales consultant who lives in Arlington, said he knows his employer, Oce{prime} USA, a digital document printing company, is monitoring his Internet use, so he does his online shopping at home. "I have [a computer] at home and I'd rather do it at home," he said. "It's more comfortable and you don't need to watch your back."

Many firms are willing to look the other way when productive employees spend a few minutes buying gifts or browsing for the best car prices from the workplace.

"The policy says the computer is not for personal use, and that applies to everybody from officers to consultants who use our equipment," CACI International Inc. spokeswoman Jody Brown said. "Occasionally an employee's mouse might slip to a Web site. I'm not sure we'd notice."

Northrop Grumman Corp.'s division near Baltimore-Washington International Airport has a similarly pliable policy. It allows "incidental access" during lunch or after work hours, spokesman Jack Martin said. But executives do not want to see employees doing all of their shopping tasks at work--or having packages delivered to the office, he said.

Privacy groups are quick to criticize electronic surveillance at the workplace, saying companies have to be careful when uncovering workers' visits to Web sites to obtain information about family or health problems.

"That is potentially the most invasive kind of monitoring that employers could conduct," said Lewis Maltby, director of the American Civil Liberties Union's workplace rights project.

Watching over employees' shoulders and banning all personal Internet use may end up hurting the companies, Maltby adds. The companies may become "ghost towns," their workers leaving for more Web-friendly firms, he said.

In an age of longer workdays and cell phones that keep employees tethered to their jobs, workers feel entitled to at least some use of their office computers so they can buy gifts, research computer prices or plan vacations. Employers with flexible Internet policies help them eliminate chores that might otherwise keep them out of the office for hours, they said.

"It has a lot to do with morale," said Nathan Hale, 23, a communications engineer for the Pentagon.

At least one study shows that many workers do not abuse their Internet privileges. A survey by Jupiter Communication found that although 20 million people have Internet access at work, some corporations had erected "firewalls" in their networks so employees could browse but not buy. Other employees fall into a group of "moral" users who rarely use their computers for personal objectives.

Hale, for example, has set limits. He uses the Internet for his own purposes less than an hour a week. He also believes checking prices of computer products online is all right, but buying them "seems a bit unethical." So he waits until he gets home, sitting in front of his own computer, to make the transaction.

Smaller employers and many Web-based companies tend to have the most relaxed policies. At Gomez Advisors, a Internet research firm in Lincoln, Mass., employees are comfortable ordering online and having their packages delivered to work.

"It certainly takes a lot less time to log on to a site then to leave during lunch and think you'll take 45 minutes to shop, when it ends up being 1 1/2 hours," said Krista Pappas, a Gomez Advisors travel analyst who estimates that she has had about 30 packages containing books, clothing and toys shipped to her workplace in the last month.

While Pappas has free rein at her computer, other employees aren't as fortunate. An Arlington technology consultant, who requested anonymity, said he has been reprimanded for surfing the Web at the office. But that hasn't stopped him from checking stock prices or buying consumer electronics. In his clients' offices, he logs on using the password of another worker. And if his consulting firm has a strict policy against this, he'll feign ignorance.

There are many employees such as the consultant, said Steve Purdham, president of the British firm JSB Software Technologies PLC, which monitors employee Internet use,

"It's frightening what people find," he said. "I often get e-mails and voice mails from companies who say, 'We didn't believe how much time was wasted.' "

One of the U.S. companies that uses JSB Software's Internet-access monitoring software took a good look at its employees' Web hits and discovered that most of the top 1,000 Internet sites had nothing to do with work.

In another instance, a U.S. manufacturer had trouble processing orders in its computer network and wondered what had caused the massive slowdown. "It found that everyone in their production unit was listening to the radio station over the Internet," Purdham said.

Another big problem is workers monitoring the action hour-by-hour on auction Web sites, said Kimberly Young, executive director of the Center for Online Addiction, who counsels workers and employers on Internet abuse.

Young said that in one case, a woman in Oregon who worked as an assistant controller for a small municipality started buying and selling small collectibles on eBay.com as a side business, but found herself unable to stop visiting the site during the day, checking on the bids, despite warnings from city officials. She was fired six months ago, Young said.

Young said workers sometimes start out their online browsing with the best of intentions, but then find themselves led astray. "People come in to work one hour early in the morning to surf and shop, but it turns into two hours," Young said. "Then it's 10:30 and they've done nothing."

Even the most avid protectors of workers' privacy acknowledge the lure can be powerful. "We all know how easy it is to fall into the Web and climb out hours later, wondering where the time went," the ACLU's Maltby said. "The Web is seductive."

Analysts such as Jupiter Communications' Melissa Shore believe that as Internet use grows, more companies will introduce policies to limit online access. That's bad news for e-commerce companies, which have relied on consumers having "free-for-all" access at work. Many online players--especially e-trade brokerage firms, computer stores and gift shops--rely heavily on daytime business.

Savvy online retailers, however, have foreseen this trend. So as U.S. companies begin building walls between their employees and the emerging marketplace online, Internet shops have devised a new tactic: Trying to create stores inside corporate networks, offering the ability to shop at certain sites online as the new generation of corporate benefits.

"Companies like Amazon.com and the Gap . . . will place their products inside these corporate intranets," Shore said.

Until then, companies that attempt to police personal Internet use may find it to be a difficult task. "Having the world at your fingertips is a mighty temptation," the American Management Association's Greenberg said.