It's getting harder to tell the difference between a Netbook and a notebook.Except when you look at the bottom line of the companies making them. Though initially thought of as a way to sell cheaper, less powerful companion devices to notebooks, Netbooks are beginning to lose their distinction, as evidenced by the new Netbooks unveiled at CES 2009. While it's good for consumers, the blurring of lines between the two could potentially be destroying the business models of PC manufacturers.

For the past year, when a laptop had a screen smaller than 10 inches, an Atom processor, and cost below $400, we'd call it a Netbook. Starting from essentially zero market penetration in late 2007, by the end of last year, roughly 10 million Netbooks have shipped, according to IDC. They now account for 7 percent of all portable PCs, an extraordinary growth rate in a short time. But exactly how the category is growing is the big question mark.

"The market is multi-faceted," said Loren Loverde, PC analyst for research firm IDC. "You don't get growth along a straight trajectory, more like growth in an amoeba. It stretches out in different directions and grows and absorbs different things."