I’ve been testing one of these new IdeaPads, a small, thin model called the U110, that’s sized to be ideal for travelers. It looks nothing like a classic black ThinkPad. It even comes in red, has swirls etched into its case, and can supposedly log you in by recognizing your face using its built-in camera.

At the same time, I’ve been trying out another similarly sized little laptop, the U2E from Asus (23571.TWO), a Taiwan-based company whose products are relatively new to the U.S. This computer has its own distinctive design: It’s clad in real leather. It also has a camera, and it can be ordered with one of the new solid-state drives, which have no moving parts, instead of a hard disk.

Both of these small laptops are subnotebooks, meaning they weigh 3 pounds or less. Like many subnotebooks, they have small 11-inch screens and somewhat cramped keyboards. And, like most subnotebooks, they are costly — an $1,899 starting price for the Lenovo and $1,999 for the Asus.

Each can only be ordered with Microsoft’s (MSFT) Windows Vista operating system, which means you can practically walk your dog in the time it takes them to start up. Each has a standard battery so wimpy that it provides poor battery life, so both companies throw in bigger batteries that provide decent power, but make the computers larger and heavier.

I wish I could recommend a clear winner between these two contenders, but both are mixed bags. The IdeaPad is lighter, thinner, and has a slightly faster processor. The Asus has a built-in DVD drive, while the Lenovo’s is external. The Asus also has the new, faster “N” type of Wi-Fi networking, while the IdeaPad is stuck with the older, slower “G” type.

Lenovo’s small, thin IdeaPad model called the U110.

The IdeaPad has two big flaws, in my view. First, it has blown the biggest advantage of its sibling, the ThinkPad: a great keyboard. The IdeaPad keyboard has huge, flat keys with slick, shiny surfaces and almost no space between them. I found typing difficult with this setup. I asked two people who are faster typists than I am to try it: One liked it, one hated it. The IdeaPad also dispenses with the TrackPoint, the little pointing stick for moving the cursor that many ThinkPad lovers revere.

By contrast, the Asus U2E keyboard, while nothing to write home about, is more conventional and more usable, with traditional tapered keycaps that provide better key separation. The mouse buttons underneath the touch pad on the Asus, while thin, were sturdier than the ones on the IdeaPad, which had a cheap feel to me.

The second big flaw in the IdeaPad is its most hype-worthy feature: face recognition, which is meant to spare you the need to type in a password to log in. In a dozen tests, it recognized me only twice. I asked my wife to try it, and it never once recognized her. It did recognize a colleague successfully, but we tried it only once with her.

The Asus’s biggest flaw is its solid-state drive. It adds $700 to the price, for a total of $2,699, but is only 32 gigabytes in size, tiny by today’s standards. To compensate, Asus throws in an external hard disk, but that’s an inconvenient solution.

You can order the Asus with a standard 120-gigabyte internal hard disk for the $1,999 price, but that’s still $100 more than Lenovo charges for the IdeaPad with the same sized drive.

Each machine has three USB ports, a video-out connector, a slot for camera memory cards, and an ExpressCard slot, typically used for cellphone modems. Neither has a built-in cellphone data modem. The Asus has three gigabytes of memory, the Lenovo just two.

In my tough battery tests, where I turn off all power-saving features, turn on the Wi-Fi, and keep music playing constantly, the Asus got about 1.5 hours and the Lenovo a miserable one hour and three minutes. This means that, even with a more normal usage pattern, you’d be lucky to get two hours out of the IdeaPad and 2.5 hours from the Asus.

With the included bigger batteries, the IdeaPad clocked out at three hours and 10 minutes, which means you could probably stretch it to over four hours with more normal use. The Asus’s bigger battery delivered an excellent five hours and 29 minutes in my test, which points to nearly seven hours in more normal use. Asus says it has tweaked its machines to improve battery life somewhat.

However, while the jumbo battery on the IdeaPad barely protrudes from the machine, and keeps the weight under three pounds, the one on the Asus U2E is so huge it looks like a tumor and pushes the weight to 3.4 pounds, well above the subnotebook cutoff.

If you’re a frequent traveler, both of these models are worth considering, but each has its own flaws.

• Find all of Walt Mossberg’s columns and videos online, free, at the All Things Digital Web site, walt.allthingsd.com. Email him at mossberg@wsj.com.

But this isn’t the much-touted Apple MacBook Air, introduced last month with all those qualities. Instead, it’s a new ThinkPad from Lenovo, the X300. While the two machines are both impressive products, they are different in key respects.

I’ve been testing the ThinkPad X300 and I have found it to be a solid, innovative laptop that will be perfect for many mobile PC users. It isn’t as sexy or inexpensive as the MacBook Air, but it has numerous features the Apple lacks, especially a wide array of ports and connectivity options, a built-in DVD drive and a removable battery.

I can recommend the X300 for road warriors without hesitation, provided they can live with its two biggest downsides: a relatively paltry file-storage capacity and a hefty price tag. This ThinkPad starts at $2,476 for a stripped-down model and at $2,799 for a preconfigured retail version with a half-size battery. The configuration I expect to be the most popular, with a full-size battery and DVD drive, is about $3,000.

The key factor in both of these downsides is the solid-state drive, or SSD, which replaces the hard disk. The SSD is fast and rugged, but today it can hold only a cramped 64 gigabytes of files and is very costly. Apple offers a MacBook Air version with the same solid-state drive for a similar high price. But Apple also has a much more affordable $1,799 model with an 80-gigabyte standard hard disk. Lenovo doesn’t.

Lenovo’s ThinkPad X300

The X300, due to go on sale next week at lenovo.com and at a few retailers, isn’t as thin as the MacBook Air. In fact, at its thinnest point it is almost as thick as the Apple is at its thickest point. And when the new ThinkPad is ordered in what are likely to be its most common configurations, it is heavier than the three-pound Apple and, in fact, fails to make the three-pound cutoff that typically denotes a “subnotebook.” Only one configuration breaks that barrier, at 2.93 pounds, and it is the stripped-down model with just a half-size battery and no DVD drive.

But the X300, which will come with either Windows Vista or Windows XP, is still very thin and light. It’s under an inch thick and even at its heaviest is only 3.5 pounds. Yet, like the Apple, it packs in a widescreen 13.3-inch display and a full-width keyboard.

Plus, Lenovo has used that extra thickness to good advantage. While the MacBook Air’s extreme thinness makes it gorgeous, it left no room for an Ethernet jack, a removable battery, a built-in DVD drive or a cellphone modem. The X300 has all these things, either standard or as options, plus three USB ports, compared with just one for the Apple. The Lenovo even offers GPS location-finding, the ability to connect to new wireless USB devices and future support for a forthcoming wireless network standard called WiMax.

The ThinkPad has another advantage: Even though its screen is the same size as the Apple’s, it is higher resolution, so more material can be seen without scrolling. Some people find that higher-resolution screens make text too small to read easily, but I didn’t experience any such problem on the X300.

In my tests, the X300 performed very well, even though it has a relatively slow processor, slower than the MacBook’s.

But the ThinkPad’s battery life was only fair, and was inferior to the Apple’s. In my tough test, where I turn off all power-saving features, set the screen to maximum brightness, turn on Wi-Fi and run a repeating play list of music, the X300 lasted three hours and five minutes. That was 24 minutes less than the comparable MacBook Air. And this was on the $3,000 configuration with a full-size battery and a DVD drive. The more basic models, with a half-size battery, would last only half as long, according to Lenovo.

MacBook Air

In more normal use, the model I tested would likely last under four hours on a charge, and the base models maybe two, compared with about 4.5 hours for the Mac.

I also tested another version of the ThinkPad, which substitutes a second, half-size battery for the DVD drive. It got five hours and 15 minutes, which means you could likely get 6.5 to seven hours in normal usage. That model costs around $2,850.

There are two more factors worth mentioning. I believe that both the Mac operating system and the software that comes with it are superior to the Windows operating system and built-in software offered on the ThinkPad. And the Mac isn’t susceptible to the vast majority of viruses and spyware, and doesn’t require third-party security software.

Also, the ThinkPad’s screen, when opened, stands significantly higher than the Mac’s, so it is less usable in a coach seat on an airplane when the person in front of you reclines.

If you’re happy with Windows, can afford the price tag, and value the many ports and connectivity options Lenovo has packed in, the thin and rugged X300 is a great choice. It’s a notable engineering accomplishment.

Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

Hard-disk drives, or HDDs, are mechanical devices. They work by recording data on a spinning magnetic platter or platters. By contrast, solid-state drives are made of chips and have no moving parts. They are close cousins to the so-called flash memory used in digital cameras, cellphones and smaller-capacity music players. They record data to special memory chips that retain their contents even when the device is turned off.

Solid-state drives have some key advantages. Because they lack moving parts, they are faster, draw less power, are harder to damage and are quieter than hard drives. Unfortunately, today’s early versions of SSDs for laptops also have two big drawbacks when compared with hard drives: They offer much lower capacity and have much higher prices.

For instance, on the newly announced Apple MacBook Air ultrathin laptop, the HDD version costs $1,799 and stores 80 gigabytes. The SSD version costs $2,798, but actually stores less — just 64 gigabytes. On the Toshiba Portege R500 subnotebook, the basic hard-drive version costs $1,999 and stores 120 gigabytes. The cheapest SSD version is $2,699 and also stores just 64 gigabytes.

Despite these limitations, I believe SSDs are likely to become more common and more popular as their capacities increase and their prices drop. Samsung, which makes the 64-gigabyte SSDs in both the Apple and the Toshiba, has already announced an SSD with twice the capacity that costs much less per gigabyte of storage.

I’ve been testing the SSD models of the Portege R500 and the MacBook Air to see how they measure up to their HDD counterparts. My verdict is that the SSD does deliver on its promises, but, in some cases, just barely.

For the small slice of users who are deeply and constantly worried about hard-disk failures, it may be worth it to pay a huge premium today for an SSD that stores less. Because SSDs aren’t subject to mechanical failures, your data are probably safer on them. But for mainstream users, my conclusion is that it’s too early to take the plunge on SSDs, and the best strategy is to wait for prices to drop sharply and for capacity to rise.

In my tests, I focused solely on comparing the hard-drive and SSD models of each machine, which I had had already reviewed in earlier columns. On the same computer, I wondered, would the SSD make a significant difference in speed and in battery life?

To measure battery life, I conducted my usual harsh test, where I turn off all power-saving software, set screen brightness to maximum, turn on the Wi-Fi and play an endless loop of music.

In this test, the SSD made little difference in the MacBook Air and, in fairness, Apple is making no claims of any significant battery-life gains on its SSD model. The SSD MacBook gave me just five more minutes of battery life. Apple says this is because its hard-drive model already uses a very low-power drive.

On the Portege R500, my first battery test with the SSD model actually yielded significantly less battery life than the hard-drive model. The reason: Toshiba ships the base SSD model with a battery with only half of the capacity of the hard-drive model.

When I swapped in the normal battery, which costs $117 extra, the SSD model gave me an added 1 hour and 21 minutes of battery life, about a 36% increase. That extra battery life likely would translate to nearly 2½ hours in more normal usage. It may be worth the huge price premium for some folks.

On both computers, the SSD was faster than the HDD models. The SSD version of the Apple booted up from a cold start, and rebooted with several programs running, about 40% faster. But the gain isn’t as impressive as it seems because even the hard-drive versions of the MacBook Air booted up in under a minute and rebooted in just a little over a minute.

On the Toshiba, which was running Windows XP, the SSD model knocked about 40 seconds off a cold boot time on the HDD version of 2 minutes and 7 seconds. On my reboot test, starting with several programs running, the SSD model was 80 seconds faster. I imagine that on laptops with the slow-booting Windows Vista, the improvements might be more meaningful.

I also tested launching Microsoft Word and Excel, and opening a couple of hefty PDF files on both machines. The SSD versions were faster. But in most cases, the gains were just a few seconds or even fractions of a second.

All in all, the SSD is a promising improvement over the hard drive, but now is not the time for most users to buy it.

Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

The new aluminum-clad MacBook Air, which I’ve been testing for several days, is billed as the world’s thinnest notebook computer. Its thickest point measures just three-quarters of an inch, which is slimmer than the thinnest point on some other subnotebooks. And it employs some innovative software features, such as fingertip gestures for its touchpad that are similar to those on Apple’s iPhone.

Apple refused to make the most common compromise computer makers employ to create their littlest laptops. Other subnotebooks — a category generally defined as weighing three pounds or less — have screens of just 10 to 12 inches and compressed keyboards. The three-pound MacBook Air, by contrast, features a 13.3-inch display and a full-size keyboard.

It’s impossible to convey in words just how pleasing and surprising this computer feels in the hand. It’s so svelte when closed that it’s a real shock to discover the big screen and keyboard inside.

But there’s a price for this laptop’s daring design: Apple had to give up some features road warriors consider standard in a subnotebook, and certain of these omissions are radical. Chief among them is the lack of a removable battery. So, while the MacBook Air will be a perfect choice for some travelers, I can’t recommend it for all. It really depends on your style of working on the road and what features you value most.

The MacBook Air, which will be available next week, costs $1,800 with an 80-gigabyte hard drive and a generous two gigabytes of memory. A second model, with a faster, cutting-edge, 64-gigabyte, solid-state drive and a slightly speedier processor, costs a whopping $3,100. The $1,800 price for the main model isn’t unusual in subnotebooks, which can easily top $2,000, although some competitors cost less.

In my tests, the MacBook Air’s screen and keyboard were a pleasure to use. The machine felt speedy, even with multiple programs running. And the laptop has the same Leopard operating system, superior built-in software, and paucity of viruses and spyware that I believe generally give the Mac an edge. I was able to install and run Windows XP using the third-party Parallels software.

But then there are those trade-offs. The sealed-in battery means you can’t carry a spare in case you run out of juice, and you have to bring it to a dealer when you need a new one. There’s no built-in DVD drive. The thin case can’t accommodate a larger internal hard disk. And the machine omits many common ports and connectors.

The MacBook Air

There’s no Ethernet jack for wired broadband Internet connections and no dedicated slot for the most common types of external cellphone modems. That means that out of the box, the MacBook Air has only one way to get on the Internet — through its fast, built-in Wi-Fi connection. If you’re out of Wi-Fi range, you’re out of luck, unless you buy an optional, $30 add-on Ethernet connector or a cellphone modem that connects via USB.

In fact, the MacBook Air has only three connectors: a headphone jack, a single USB port and a port for connecting an external monitor.

That single USB port is a problem, because so many peripherals use USB. You can buy a tiny, cheap USB hub that adds three more ports, but that’s yet another item to carry.

The lack of a DVD drive is partly solved by some clever software Apple included that lets you “borrow” the DVD drive on any other Mac or Windows PC on your network, so you can transfer files or install new software from a CD or DVD. This worked fine in my tests, in which I installed several new programs from CDs on remote computers, but it requires disabling third-party firewalls on Windows machines. It also doesn’t work for installing Windows on your Mac, for watching DVDs, or for playing or importing music. For those tasks, you need an external DVD drive. Apple sells one for $99.

In my standard battery test, where I disable all power-saving features, set the screen brightness at maximum, turn on the Wi-Fi and play an endless loop of music, the MacBook Air’s battery lasted 3 hours, 24 minutes. That means you could likely get 4.5 hours in a normal work pattern, almost the five hours Apple claims.

But the MacBook Air has another downside: its screen height. Because of the larger screen, the lid stands higher when opened than on most other subnotebooks. So it isn’t as usable as some competitors when the seat in front of you in coach on a plane is reclined.

If you value thinness, and a large screen and keyboard in a subnotebook, and don’t watch DVDs on planes or require spare batteries, the MacBook Air might be just the ticket. But if you rely on spare batteries, expect the usual array of ports, or like to play DVDs on planes, this isn’t the computer to buy.

• Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

Most of the major specs I recommended two weeks ago in my annual spring guide to buying a computer hold true for laptops as well as desktops. That guide can be found at walt.allthingsd.com/guide. But buying a portable involves additional factors, so here are some tips for making laptop purchases.

First, you may want to wait to get that new laptop until later this year or early in 2008. There are a number of interesting new hardware features coming. One is called a “solid-state drive,” or SSD, which replaces the traditional hard disk with a faster drive made of memory chips like those used in digital cameras. Another is a “hybrid hard drive,” or HHD, which combines memory chips with a standard hard disk, for faster start-ups.

Also, more and more laptops will be using light-emitting diodes, or LEDs, to light up their screens — a method that promises to be both brighter and less power-hungry.

You also may want to wait for laptops with a new type of Wi-Fi wireless networking built-in. It’s called “N,” and promises to be faster and to have longer range.

For Windows Vista users, another new laptop feature coming soon is a small screen on the lid called a SideShow, which can display calendar appointments and new emails.

Even if you don’t wait, there are some features to know about that aren’t available on most desktops. One is a built-in Web camera and microphone, highly useful for making video calls and recording videos to be posted online. Another is a feature that allows you to play music, videos or DVDs without booting up Windows.

In addition, if you travel a lot, you may want something called a built-in WWAN, or Wireless Wide Area Network. This is essentially a cellphone modem that makes Internet connections over a cellular carrier.

Another key feature is a new kind of slot on the side of most laptops for add-on cards, like wireless modems. It’s called an ExpressCard slot and, confusingly, it comes in two sizes. Your old-style cards, called PC Cards, won’t fit in these new slots, so unless you want to buy new cards, you might look for a laptop that has both the old and new slots.

Battery life, weight and size remain crucial on laptops, unless you are buying a huge “desktop replacement” laptop, which will rarely leave the house or be unplugged. For everyone else, I recommend finding a laptop that offers at least three hours of battery life on a single charge, without requiring you to dim the screen so much you can’t see anything.

Most laptops cluster around the six-to-seven-pound range, which is fine for occasional travel, or for carrying between classes, or between home and office. But if you are a frequent air traveler and have the budget, shoot for a laptop that weighs four pounds or less and is small enough to use on a seat tray in coach even when the person in front of you reclines.

The most expensive laptops are at the extremes–huge, multimedia machines and ultra-portable models for hard-core road warriors. Most well-configured Windows laptops, with typical 15.4-inch screens, are between $900 and $1,500.

I find that laptops with 13.3-inch widescreen displays make a nice compromise between mobility and power. At the moment, there are very few brand-name models in that size, notably Apple’s $1,099 MacBook, which weighs 5.2 pounds; and Sony’s Vaio SZ line, which weighs 4.1 pounds but costs roughly twice as much. More 13.3-inch models are coming later this year from other manufacturers.

Finally, there’s the perennial issue of Windows versus Mac. Apple’s two laptop lines, the MacBook and MacBook Pro, are very good. They have better built-in software than any Windows laptop I’ve seen and don’t suffer from the security issues that plague Windows. And they can even run Windows software, if you need that.

But the Mac laptops lack some features that are common on Windows portables, such as slots for camera memory cards and built-in cellular modems. And the MacBook even lacks an ExpressCard or PC Card slot.

Among Windows machines, I think Sony and Lenovo make especially well-designed laptops, but almost any name brand would be fine.

Addendum: I’m happy to say there is a new, expanded and redesigned online home for all my columns. It’s at walt.allthingsd.com and access is free. It contains the current versions of the columns with the accompanying videos, plus a searchable two-year column archive and a new blog called Mossblog, which I will update occasionally.

This new column home page is part of a larger new Web site called All Things Digital, at allthingsd.com. In addition to my columns and blog, it contains technology news, analysis and opinion from journalists Kara Swisher, Katherine Boehret and John Paczkowski, and guest blogs from prominent technology figures.

My columns will still be published on The Journal’s main Web site, WSJ.com, which is available to paid subscribers and includes a much larger archive, going back more than a decade.

• Email me at mossberg@wsj.com