By Scott Nesbitt - September 26, 2010

Portable computing has definitely evolved over the years. We've gone fromluggable computers to actual laptop andnotebook computers, toPDAs, netbooks, and smartphones.

For getting real work done while on the go, nothing beats a laptop or notebook computer. Or does it? Another alternative, that gives you the flexibility and portability of a notebook but without the bulk, is an ultra thin laptop.

OK, most modern laptops aren't all that chunky. And netbooks even less so. But the form factor of an ultra thin is really a sight to behold.

Inhabiting the middle ground between a full-blown laptop computer and a netbook, an ultra thin laptop weighs in at around three pounds and packs a 13 inch (or bigger) screen and a full-sized keyboard.

Back in 2008, MacBook Air kick started the demand for ultra thin laptops. Since then, just about every major hardware manufacturer -- including companies like Toshiba, Acer, Lenovo, Dell, Asus, and Gateway -- has jumped on the bandwagon.

A combination of portability and power. I'll talk about the power in a moment. While somewhat larger than a netbook, an ultra thin weighs about as much as a netbook. Even so, with a 13 inch screen and thickness of under an inch an ultra thin laptop can comfortably into a briefcase, a laptop case, a backpack, or a courier bag.

You get a bigger screen (no more squinting!), and large keyboard and trackpad. Perfect for anyone who finds the keyboard and trackpad on a netbook too confining.

Remember, though, ultra thins are definitely not replacements for adesktop computers or a full-fledged laptops. But they are definitely a strong alternative to netbooks.

That last couple of paragraphs gives the impression that ultra thinsare woefully underpowered. They aren't. The processors are specially-designed for for mobile devices and they use very little electricity. The processorsin ultra thin laptops range in speed from 1.2 GHz to 2.66 GHz. At the low end, you're getting processor speeds comparable to the average netbook. At the higher end, it's the same processor that you'll find in a notebook.

The low-voltage processors help ensure that an ultra thin laptop doesn't use too much power. That means longer battery life, which is important when you're computing on the go. It also means that an ultra thin runs cooler.

As for the rest of the innards, an ultra thin can pack anywhere from 2 GB to 8 GB of memory, a harddrive of up to 500 GB, and a fast graphics card.

Admittedly, you won't be doing any heavy work -- like video or audio editing, or even high-powered graphics -- on an ultra thin. But ultra thins pack more than enough power to do everyday work like word processing, working with spreadsheets and presentations, using the Web, or doing some Web development work.

And by that, I mean ports. Of course, you get multiple USB ports, a port for network connections, and (in many cases) a reader forSD cards. They also pack video connectors (useful when giving presentations), and audio jacks.

One complaint about the MacBook Air was that it didn't have aCD/DVD drive. Many of the newer ultra thins from other manufacturers do have an integrated CD/DVD drive, and it doesn't add much (if anything) to the thickness of the device.

Look somewhere else. Ultra thin laptops aren't cheap. On average, they're more expensive then a netbook or even a budget laptop computer.

A quick, unscientific survey of online retailers revealed that the price of an ultra thin ranges from around $450 to about $900, with $699 being the average. Not cheap, but not prohibitively expensive.

While there hasn't been an explosion of ultra thins, there are quite a few on the market. Like what? Here are a few.

The MacBook Air is still going strong. Since 2008, it's been updated a couple of times. Lenovo, which bought IBM's computer business, has the ThinkPad X series. The hardware is solid, and the prices aren't too bad.

Dell's Vostro 3300 is a quite a good deal. It has some great specs, and it's price comes in at under the $699 average I found. The Asus UX30 is smaller and lighter (in specifications, size, and weight) than many of its contemporaries but it packs the goods to get work done.

If you're into style and function, take a look at the Acer TimelineX. It's sleek, strong, and comes with high definition widescreen video. Finally, the Linux users out there might want to take a peek at the Hoverboard X30 from ZaReason. You get all the advantages of an ultra thin and can get your favorite Linux distribution installed on it.

It all depends on what you need in your portable computer. I'm biased, though. My main computer is a laptop, and I was an early adopter and enthusiastic user of netbooks. But I don't want to lug my main computer with me, and I started to find netbooks to be a bit cramped and underpowered. I went ultra thin, and have no regrets.

If you're a professional, then an ultra thin laptop can be a worthwhile investment. You get portability and power, with the hardware that you need to do your work. On the other hand, if you're on a budget (say, a student or home user) then an ultra thin probably isn't your thing. If you want something portable, go with a notebook computer or a netbook.

When making your decision, think about how much you're going to use an ultra thin. If it's going to get heavy use, and if it's going to pay for itself in a short time, then an ultra thin is definitely a worthwhile investment. Especially if it saves wear and tear on your main laptop computer.