Picking the top netbook is a matter of choosing among small differences. After all, most of the bestselling netbooks offer remarkably similar features: the Intel Atom chip, a screen about 10 inches wide, and a low price that makes PC makers sob uncontrollably.

The factors that comprise the top netbook – for you – are less-than-huge differences in keyboard size (chiclet or almost full size), price (around $350), and a category loosely described as “special netbook options.” These include options like a slot for a TV tuner if you simply must watch Simon Cowell while you’re on the train.

But these simple options might not be so simple for long. The netbook market is changing – by the moment.

Why? Because netbooks are prompting a revolution that just might topple giants. The dominant Intel chip will soon be threatened by cheaper chips, like the cellphone ARM chip or Qualcom’s Snapdragon. The dominant Windows XP (which now runs about 80 percent of netbooks) will be challenged by Linux and Google's Andriod OS. (Yes, the netbook might be the platform that finally delivers Linux to the masses. Or not, if reports of Windows' growing netbook market share are accurate.)

Consumers, meanwhile, face a blizzard of new netbooks. While early netbooks were designed for Third World children, these cheap portables quickly attracted more affluent users. When Asustek debuted the groundbreaking Eee PC in the fall of 2007, students and professionals alike responded like the second coming of Elvis.

The funky 7-inch machine flew off the shelves – more than 350,00 sold in mere months. Other PC makers saw the party and soon introduced a profusion of netbooks. By the end of 2008 users bought somewhere between ten to fourteen million netbooks, depending on who’s counting.

Zooming netbook sales taught the Dells and Toshibas of the world a sobering truth: consumer aren’t hungering for the old school, souped-up laptop. Instead they want a zippy hyper-mobile unit that delivers for cheap.

Or, actually, what they really want – and here’s where PC makers begin to cry – they want a great portable and they want it super cheap.

That, in a nutshell (or should it be ‘netshell’?) is the back story to the Netbook Revolution. It’s estimated that by 2010 netbooks will comprise a whopping 12 percent of the laptop market – from zero just a few years back.

The next step? Virtually free netbooks. AT&T, an unlikely radical, has already breached the barricades: a netbook for a measly $50 if you sign up for Net service. (Alas, it’s so far available only in Philadelphia and Atlanta.)

But no, you can’t wait for the offer to come to your town. You need one now. Based on the excitement, netbooks make you happier, healthier, even sexier; they’re as essential as fruit and vegetables – and far more fun; and soon, four out of five dentists will be recommending them.

So here’s a comparison of the top units. The question: which netbook is best for you?

ASUS 1000HE // Acer Aspire One // Samsung NC10 // Dell Inspiron Mini 9/Mini 10

HP 2140 Mini // Lenovo IdeaPad S10/S10e // MSI Wind // Sony Lifestyle PC