I apparently can't follow my own advice: I recently purchased an ASUS Zenbook, one of a handful of first-generation Ultrabooks currently in the market and the one, I think, that most closely resembles Apple's MacBook Air. And while I'm very enthusiastic about the Ultrabook form factor overall, I'm not sure I can recommend this particular rendition, at least not universally.

As a backgrounder, you may recall that I experimented with using a 13-inch MacBook Air with Windows last year. That experiment, which I ultimately deemed a failure, led to two articles, MacBook Air + Windows 7, Part One: The Best Of Both Worlds? and MacBook Air + Windows 7, Part Two: An Imperfect Storm.

The MacBook Air is a fine machine, but it's not ideal as a Windows laptop. First, it's expensive, with a base model, 11-inch version starting at $999 and the more mainstream 13-inch variant starting at $1299. Compare those prices to the PC world, where the average cost of a Windows laptop is now about $450. (That said, Ultrabooks tend to cost closer to $1000.)

Adding to the misery is the non-standard MacBook Air keyboard, which takes some getting used to and isn't necessarily insurmountable, the lack of optimal Windows drivers (which we can all agree Apple does on purpose), lackluster power management controls (again, just on Windows and no doubt related to the previous point), and the fact that you really need to keep at least a minimal Mac OS X partition on there to perform vital firmware upgrades. This latter point cuts into disk space, which is crucial given the relatively low storage allotments on the SSD-based Air.

What this all adds up to is that the MacBook Air is not an ideal Windows machine. But it's still very clear that this device is beautiful to look at and, thanks to its thin profile and low weight, an ideal travel companion. If only it were better suited to running Windows.

Enter the Ultrabook.

On the face of things, the Ultrabook is a bald-faced attempt to copy Apple's design for the MacBook Air and apply it to Windows-based PCs. And there's some truth to that, of course. But as I wrote last August in Intel's Ultrabook Scheme: Is This The Future Of PC Computing?, the Ultrabook is really a platform with a roadmap, and that roadmap specifies three generations of devices that will culminate (for now, at least) with Windows 8.

At the time this article was written, any Ultrabook you see in the market--the ASUS Zenbook I'm using, the original Ultrabook, the Samsung Series 9, the Acer Aspire S3, or the Toshiba Portege Z835--is a first generation Ultrabook. And that means they sport second generation Intel Core i-Series ("Sandy Bridge") processors. They're thin and light and get decent battery life, and many--like the ASUS--are a bit too much about copying the MacBook Air.

Second generation Ultrabooks will ship throughout 2012. What separates them from first-generation devices is that they will include more efficient third-generation Intel Core i-Series ("Ivy Bridge") processors. So they should, in general, offer better performance, better battery life, and, most important, allow for even thinner and lighter form factors. That said, most of these machines won't move very far beyond the basic look and feel of the MacBook Air.

Representative second-gen Ultrabooks include the Acer Aspire S5, Dell XPS13, HP Envy 14 Spectre, Lenovo ThinkPad T430u, Samsung Series 9 (2012), Sony VAIO Ultrabook, and many, many others. Over 100 such machines will ship this year, and most were announced in January at CES.

If you're in the market for an Ultrabook, I generally recommend waiting for at least a second-generation model, assuming this isn't a buying emergency. But lingering on the horizon is the third generation Ultrabook platform. And this is where things get really interesting.

Third generation Ultrabooks will be hybrid devices where the "guts" of the PC sit behind the screen, not under the keyboard. This means they can be used as pure tablet devices, slates, sans keyboard. But when you plug that slate piece into a keyboard dock, they become laptops. These hybrid devices will ship with Windows 8 in late 2012. I believe the first models will use Ivy Bridge processors, but it's conceivable that an even more efficient Intel chipset will arrive by early 2013 too.

You may have heard of the Lenovo IdeaPad Yoga, a hybrid Windows 8-based machine of a different stripe; if not, check out my overview in Windows 8: Lenovo IdeaPad Yoga Flip. This device is not technically an Ultrabook, but it does share many Ultrabook design points and also suggests a future of more diverse Windows-based devices.

True third generation Ultrabooks will more closely resemble an iPad with a clip-on keyboard base. There are also some interesting Android-based tablets hitting the market that offer this type of functionality; a good example is the ASUS Eee Pad Transformer Prime.

We're still some months away from these new devices, of course. For now, I'm using an ASUS Zenbook UX31, which is very good but not spectacular. (I'll be replacing it with a second-gen Ultrabook when possible, ideally the ThinkPad T430u.)

The ASUS is a lot less expensive than a comparable MacBook Air at about $999. It's attractive looking, if a bit too similar to the MacBook Air. Separating it from Apple's device is a metallic finish I don't really care for but others seem to like, USB 3.0 ports, and killer audio for a portable machine. On the flipside, there's no backlit keyboard, which I'd prefer.

Actually, the keyboard is a bit of a sore spot, all the more so since I'm used to the stellar keyboards found on Lenovo's superior ThinkPads. The keys are flat and shallow, as on a Mac, and really need to be struck fully to work. It's not ideal for someone who types a lot, as I do.

Much about the machine is excellent. Its thin and light and I enjoyed both of these aspects on a recent business trip to Colorado. It was much easier to travel with than the ThinkPad Edge 420S I've been using for the past year. Performance and battery life are both excellent, with the latter coming in somewhere close to 7 hours. The device springs to life from sleep in about a second, which is amazing for a Windows PC.

Like most Ultrabooks, expansion is tight. There are two USB-type ports, but to get Ethernet you have to use a bundled USB-to-Ethernet adapter, stealing one port. ASUS also tosses in a nice micro VGA-to-VGA adapter, and there's a micro HDMI adapter if you want to add your own. An SD card slot rounds out the holes.

There's no optical drive. I happen to prefer such a design, which of course contributes to the device's thinness. But if this is a need, you'll want an external drive.

The ASUS trackpad is decent for what it is, but I prefer the accuracy of the ThinkPad's "eraser head" nubbin, so I brought along a mouse, somewhat obviating the ASUS's inherent weight and size benefits.

If you are in the market for an Ultrabook right now, for some reason, the ASUS Zenbook is a good choice. Its not perfect--what is?--but I think it represents the apex of the first generation Ultrabook market, such as it is. If you can wait two to four months, you should. You'll soon have a cornucopia of second-gen Ultrabook options from which to choose, and many of those, I think, will offer significant advantages over what's available today.

Looking even further ahead, Windows 8 will unleash further Ultrabook designs, including hybrid machines that could be truly interesting, especially if Windows 8's Metro-style environment takes off with users. We'll see. But whatever happens, the next year is going to be an amazing one for portable computing.