Twelve years ago, Compaq shocked the PC world with a sub-$1,000 PC.

Now, some companies are talking about the sub-$50 desktop.

NComputing, which specializes in thin clients, says that schools and businesses can now buy its energy-efficient desktops for $45 after rebates. In some cases, the desktop conceivably could be acquired for free, says the company.

Chalk it up to utility rebates. The company specializes in thin clients, i.e., intelligent terminals. Thin clients have smaller processors and fewer components than standard PCs. NComputing's desktops can fit inside of a box that looks like it should hold a souvenir coffee mug. (See video here. Finest thin-client movie ever.) On their own, thin clients aren't as powerful as PCs – most of the computing takes place on servers in data centers.

Thin clients, though, also only use a fraction of the power. NComputing's desktop consumes as little as 1 watt of power Even when the server energy is added in, thin clients use less power, say advocates, although the total energy is sharply debated.

As a result, utilities have been offering rebates to entice schools, government agencies and others to switch. NComputing's basic desktop costs $70. Seattle Light, a utility in the Northwest, however, offers a $25 rebate on each NComputing device. That drops the price to $45.

Duke Energy, meanwhile, offers a rebate of 8 cents per kilowatt hour.  San Diego Gas and Electric, Southern California Edison, and BC Hydro have similar or higher rebates. In all, it has qualified for rebate programs in California, Illinois, Indiana, Kentucky, New York, North Carolina, Ohio, Washington, and British Columbia, Canada. It is also working with agencies outside of utilities, such as the Illinois Department of Commerce & Economic Development, on energy-reduction incentives.

The rebates and rising energy prices are breathing life into a market that proponents have claimed is the next big thing for close to twenty years. The Regional Transportation District (RTD) in Denver, for example, is in the middle of replacing 800 PCs with thin clients. It has 1,000 computers on its network. The swap is expected to save close to $600,000 in hardware and maintenance costs over the next eight years.

The costs of the swap were partly defrayed by rebates from Xcel Energy, the local utility, said Trent Ratcliff, the IT Infrastructure Manager. (The RTC has bought thin clients from Wyse, not NComputing.) NComputing, meanwhile, has planted over 1.5 million of its desktops in the market: schools in emerging markets like India have been big customers.

The energy debate, however, is far from over. Corporations that move from desktops to thin clients have to bulk up on servers, notes Jon Haas, director of the Eco-Technology Program office in Intel's Digital Enterprise Group, Servers draw power and, because they are in data centers, they have to be cooled with air conditioning. Together, those two things cause thin client power savings to evaporate, he argued.

"People are going to realize that thin clients have their limitations," he said.

Historically, employees have also chided at using thin clients. Slow, chugging performance has been a chronic complaint. PC power consumption has also continued to drop. Thin client backers say a lot of these problems have been solved, but it will be an uphill marketing struggle.

It is a partisan debate worth watching.