Two weeks of wanderlust in Eastern Europe came to a screeching halt for Robbin Steiff when, over breakfast one morning, her husband Paul screamed, "Why do we have to spend half a day in every new city finding an Internet cafe?"

Steiff, a highly driven marketing consultant from Mt. Lebanon who sheepishly admits she's a "heavy user" of the Internet, wasn't scouring for places to check her work e-mail. She simply wanted to describe each place they visited to their two daughters, who were back home at camp. "They are your children, too!" she hollered back.

Like many others, Steiff is an Internet addict. More than 137 million Americans spend at least part of their day online, and when it is unavailable, many suffer withdrawal much as they would if they had to go without coffee or cigarettes. They have come to rely on the Web to manage increasingly hectic personal lives, and can't imagine life without it.

"The Internet really is one of the primary tools that people use to balance work and personal life," said researcher Ben Jacobson, whose Evanston, Ill.-based firm Conifer Research recently conducted a study to gauge what happens when ordinary Americans are forced to stay off line.

Local attorney David Cohen said he feels naked if he leaves the house without his cell phone and "crackberry" -- the popular nickname for the Blackberry brand mobile e-mail and phone device that many professionals keep closer to them than their children.

"In the old days, you remembered your watch and wallet. Now, you have to remember your cell phone and Blackberry," said the partner at Downtown-based Kirkpatrick & Lockhart, Nicholson Graham.

With 80 to 90 e-mails to answer each day, Cohen said his Blackberry keeps him on the defensive with clients. It used to be that, "when we dealt with snail mail, you were being prompt if you answered a client's question in a couple of days. Now, you're expected to answer e-mail in a couple of hours."

Cohen's firm paid $200 to make sure he was connected to the Internet while on a family cruise to Scandinavia last year. "It was great, I didn't have to take a week to dig myself out from e-mail when I returned.''

It helped, he said, that his wife, a University of Pittsburgh developmental psychologist, is just as heavy an Internet user as he is, so she didn't mind the time he spent on the job while on vacation.

Cohen insists he's not an Internet-aholic, just an organized gadget geek. A father of three who is active in his community, Cohen's essential tools include a laptop, Blackberry and nonstop wireless Internet connection.

The Internet, he said, actually has allowed him to spend more quality time with his family. "It's gotten me home, whereas in the old days, I would have worked late at the office or had to go back to work."

Staying "connected" is akin to ball and chain for local tech firm Laurel Networks President and Chief Operating Officer Atul Bansal, who last year faced the wrath of his six and 10-year-old sons.

The pair got tired of having dinner frequently held up for hours while Bansal, having arrived home from work, sat in the car in their McCandless garage, sifting through e-mails on his Blackberry and talking on his cell phone. After dinner, he'd sit in front of the TV with his family, tapping away on his laptop.

"They said, 'You're not even talking to us -- you're just working on e-mails," said a somewhat guilt-ridden Bansal, who continues to struggle with his children's desires and his desire to be online.

Self-professed Web devotees say it's a good, not a bad, thing. They contend the Internet has revolutionized their ability to manage their lives and control how and when they deal with everyone -- from co-workers to the electric company.

Bansal noted that he's able to stay connected far more cheaply with his family in India and his business contacts worldwide thanks to e-mail and its newer cousin, instant messaging. E-mail, he added, is far less intrusive than the phone.

And Steiff, the marketing consultant, has abandoned her checkbook because she now pays all of her bills online, a convenient and quick way that ends all the concern about bounced checks and float.

Jacobson, whose study cut 28 adults off from all things Internet for two weeks last summer, said the participants did discover some benefits to be off line.

For one, many increased their level of physical activity during the ban.

"Part of that was the summer," which lends itself to more outdoor activity, he said, but a lot of it had to do with the simple fact that participants no longer were glued to their laptops or Blackberrys.

Still, symptoms of Internet withdrawal were clear, Jacobson said, noting several study participants said it almost seemed like the computer was "calling out'' them, much as someone on a diet might "hear'' cake or ice cream whispering their name.

That was Bansal's experience while on a trip to the Bahamas last August, when there was no access to the Internet anywhere. "The first few days were really weird,'' he said. "You think you are missing out on life, basically."

Jacobson said many people don't realize how the Internet and their dependence on it has snuck up on them.

He cited study participants who realized they didn't have any friends that they didn't communicate with other than through the Web. One guy couldn't get in touch with anyone because all his contact information was stuck in his Yahoo e-mail address book.

The Web also is updating the Norman Rockwell views of the family at home.

Instead of sitting around a fireplace or television, the Steiffs often can be found on their top floor computer room, each sitting at one of four workstations for every family member. Often Steiff, her husband, and two teenage daughters will be in the room together, working, e-mailing and surfing the Web simultaneously.

For Steiff, a frequent e-mailer since the '80s, it is the normal, modern-day view of families at home.

She "does everything online," even communicating with her daughters -- even when they are in the same room. She said she doesn't want to function without the Internet.

"I couldn't understand why my husband didn't get it," she said of their little tiff over her need to constantly check her e-mail while on vacation.

"I love it. It's a little bit like someone who's addicted to nicotine."