When Apple released the MacBook Air, someone viewed the sleek notebook as an opportunity to make fun of clunky, old Dell on YouTube with a parody ad. But what if Dell is about to have the last laugh in the ultralight laptop race?

A recent dig through Dell’s trademarks turned up a couple of curiosities – “Adamo” and “Adamo by Dell.”According to the documents, the trademarks cover computer hardware, including possibly desktops and laptops.

The whole “Adamo by Dell” bit sounds rather fancy for a company that lumps all of its computers under just a handful of brands. But, apparently, this computer isn’t your regular Dell computer. It has its own Web site after all, which says the product is coming soon.

Throw Adamo and Dell into a search engine, and you get nothing. Well, make that almost nothing.

A luxury goods publication appears to have some early marketing collateral from Dell for Adamo. “Rumor has it that Dell is coming out with a computer called Adamo that will rival the MacBook Air.

Microsoft has long been worried about Linux competition in the server market. When it came to ordinary PCs and laptops, however, it knew it had little to fear.

But that was then. Now Microsoft may fear Linux on the desktop as much as it does the Mac. It’s finally taking Linux seriously as a desktop operating system, and it has designed Windows 7 to kill it.

The threat to Windows comes entirely from “netbooks” — lightweight, inexpensive laptops that typically use Intel ‘s low-powered Atom processor and don’t come with substantial amounts of RAM or powerful graphics processors. They’re designed mainly for browsing the Web, handling e-mail, writing memos, and taking care of simple word-processing or spreadsheet chores.

Clearly, the future is in netbooks. And that has Microsoft worried. Netbooks can’t handle Vista’s hardware demands, so XP is the only Microsoft operating system that runs on them. But Linux is ideally suited for lower-powered notebooks.

The result? Acer and Asustek, which account for 90% of the netbook market, are using Linux on about 30% of their low-cost notebooks, according to Bloomberg. Making matters worse, if Linux is used on those netbooks, it means that Microsoft Office isn’t. So Microsoft takes a double hit every time someone buys a Linux netbook.

Microsoft isn’t just worried about ceding 30% of the netbook market to Linux. It’s also worried that if people get used to running Linux on netbooks, they’ll consider buying Linux on desktop PCs as well.

Microsoft, though, has a not-so-secret weapon against Linux: Windows 7. Its new operating system, slated to be introduced sometime next year, is designed to work fine on netbooks. In fact, at Microsoft’s recent Professional Developers Conference, where the pre-beta of Windows 7 was unveiled, Windows Senior Vice President Steve Sinofsky showed off Windows 7 on his Lenovo S10 and said it used less than half of the netbook’s 1GB of RAM.

When Windows 7 ships, expect a massive marketing blitz pushing it on netbooks with special deals, and netbook hardware taking advantage of Windows 7 capabilities, including touch screens.

In fact, the blitz has already begun. Asus CEO Jerry Shen announced that he plans to release versions of the Eee PC powered by Windows 7 in mid-2009, including a touch-screen version.

Despite Microsoft’s killer instincts, I don’t think Linux netbook sales will stop dead. There will always be a niche for them. But within a year of the Windows 7 launch, Linux market share will drop. The high point for Linux netbook sales will be from now until the launch of Windows 7. After that will come the inevitable decline.