Never underestimate the power of a good idea to transform the world. The $100 laptop is just such an idea.

No, you can't buy one, at least not yet. It doesn't exist. The idea, though, holds hope for plugging the world's poor into 21st-century technology.

The $100 laptop is the brainchild of Nicholas Negroponte, co-founder of the Media Lab at the Massachusetts Institute of Technology. Negroponte, standing alongside U.N. Secretary-General Kofi Annan, unveiled the first working prototype at a U.N. information society summit in Tunis last month.

As envisioned by Negroponte, the laptop would have wireless Internet capacity and run on some variation of open-source, Linux-based operating software. It would include word processing, a Web browser and e-mail. It would be plugged into an electrical source or powered by cranking its attached handle. It would be sturdy, durable, mobile and cheap.

Negroponte has established a non-profit association called One Laptop per Child, which has start-up funding from a handful of companies including Google, News Corp. and Advanced Micro Devices. The association plans to sell the laptops at cost to government education ministries that would distribute them to children. According to Negroponte's ambitious timetable, the $100 laptops could be on their way by late next year to Egypt, Brazil and Thailand.

There are endless reasons to assume that this can't be done. It has been tried before: Simputer's plan several years ago to distribute low-cost handheld computers in India went nowhere. It's impossible to produce even a stripped-down laptop for such a low price. What good will built-in WiFi be if there's no WiFi access? Depending on poor countries to pay even the low price of $100 is unrealistic. Poor people need clean water, health care, reliable food sources and shelter far more than they need laptops.

A writer at Slate.com recently called the $100 laptop a "huckster's gambit — poorly thought out, overly ambitious and too sexy to be true."

But imagine for a moment the possibilities such a machine could open up to poor children around the world. Even as rich, developed countries — including urban parts of China and India — become ever more connected, the children in vast stretches of the world remain isolated and stuck in poverty. People in cities such as Chicago and Shanghai Google and e-mail away. Those living in poor villages in Africa, the Middle East, South America and much of Asia aren't connected to the 21st-century economy.

Technology has allowed people from Boston to Beijing to Bamako to become friends, mentors, business partners. Yet much of the world still doesn't have that opportunity. The $100 laptop could create the economic and cultural links that have been missing.

Negroponte believes it is worth taking a gamble on that. So does Hector de Jesus Ruiz, the Mexican-born CEO of Advanced Micro Devices. AMD is one of a handful of companies involved with Negroponte's non-profit group. AMD is also working on developing a low-cost computer with built-in Internet access that would be aimed at those who make $5,000 to $10,000 a year. The company thinks it might cost about $200.

Ruiz's drive to expand technology's reach beyond the developed world was inspired by professor and entrepreneur C.K. Prahalad, who believes the world's 4 billion rural poor people should be viewed as potential customers rather than victims of their circumstances.

Case in point: Prahalad argues that if the poor can't afford to buy shampoo, that's because shampoo comes in large sizes with expensive packaging. Sell shampoo in a simple, one-use packet, and it becomes affordable.

Shampoo, laptops ... Ruiz and Negroponte believe those at the bottom of the pyramid are potential consumers waiting for the chance to connect. Even as rich, developed countries become more connected, the children in vast stretches of the world remain isolated.