Slideshow: 10 Hot Netbooks - From Pricey to Dirt Cheap

"They love [a] netbook, as long as it's a low-powered companion, accessory PC," said Stephen Baker, an analyst with NPD Group, a market research firm that specializes in watching retail sales. "But they don't want to sell too many of them."

Microsoft's quandary is that while the jump in netbook sales means more copies of Windows are sold to computer makers, the versions suitable for the smaller systems -- primarily the ancient Windows XP Home -- are its lowest-priced. Every netbook, then, is a lost sale of a so-called "premium" edition of Windows.

"It has a vested interest in minimizing cannibalization as much as possible," said Baker, referring to netbook sales eating into those of more powerful, and higher-priced, notebooks that run, for instance, Vista Home Premium, or in the future, Windows 7 Professional.

One move Microsoft has made to keep the netbook in its place is to limit sales of some editions of Windows 7 to computers with small screens and low-powered single-core processors. The Malaysian Web site TechARP.com, which leaked the specifications last week, said Microsoft will sell Windows 7 Starter, Windows 7 Starter for Small Notebook PC and Windows 7 Basic for Small Notebook PC only to OEMs planning to install those editions on netbooks with 10.2-in. or smaller screens that use a power-miser processor running no faster than 2GHz.

"They can make the format stick with OEMs," said Baker. "But can they minimize the price declines that are pushing PCs under $400? I don't know if they can do that."

What Microsoft can do -- and will -- said Baker, is use those Windows 7 specs to minimize the potential damage netbooks pose to its revenue, and, if possible, coax users into moving up to editions with a larger profit margin.

"What they can do by forcing specs is [force] that netbook to remain an extra PC," Baker said, pointing to the low-powered processor requirement in particular. "They'd like to take people off the idea [of netbooks] and move them back to something that answers some pieces of what people want in a netbook -- small and light -- but more powerful. Then they have a win."

A more powerful, more traditional laptop, of course, would more likely run Windows 7 Home Premium, Professional or Enterprise, all of which Microsoft considers part of a premium line that makes more money per unit when sold to OEMs.