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.

As always, this is a general guide aimed at mainstream, nontechnical consumers who dwell on common tasks such as email, instant messaging and surfing the Web; managing and lightly editing photos, videos and music; and using basic office applications. It is not intended for heavy gamers, video producers or corporate buyers.

There’s a vast variety of laptop models, but this guide is meant to cover the most common types of laptops, those with screens from about 12 inches to 17 inches, and weights ranging from around 2.5 pounds to 7 pounds.

For this column, I’m not including the category of tiny machines now called netbooks, with screens under 10 inches. I am also ignoring the huge, heavy laptops with screens larger than 17 inches that are primarily aimed at gamers.

Even the remaining mainstream machines range wildly in price, from bargain-basement models at $350 to high-end ones that can top $3,000. In my experience, the top brands for technology and reliability are Apple and Lenovo’s ThinkPad line, but various models from Sony, Hewlett-Packard, Toshiba and Dell are also worth investigating.

So, here is a quick guide to the key factors you should consider when buying a laptop.

Size: If you are a constant traveler, think about the subnotebook models, which generally weigh 3 pounds or less. There are two types of these. The classic subnotebook has a small screen, 12 inches or less, and a cramped keyboard. This year, a new type emerged, with a full keyboard and a normal 13.3-inch screen packed into a thin, light body. There are two of these: the MacBook Air from Apple and the Lenovo ThinkPad X300. All subnotebooks are relatively costly, typically ranging from $1,500 to over $3,000.

If your laptop will mostly stay at home, the office, or in class, a 5-7 pound machine with a screen of either 13.3 inches or 15.4 inches is the best bet. A well-equipped model in this class is likely to run you between $800 and $1,200. Typical models in this class are the Dell Inspiron 1525, the HP dv6700 and the Apple MacBook.

Windows vs. Mac: This is the eternal question. In my view, Apple’s Leopard operating system is faster, better and far less prone to malicious software than Microsoft’s Vista operating system. And the Mac laptops also come with better built-in software. The $1,099 MacBook is a solid, fairly priced machine, and the $1,999 MacBook Pro is even better. Both also can run Windows.

But Windows laptops are often less expensive, tend to have a greater variety of ports and slots, and come in more styles and sizes.

Apple’s MacBook

Operating system: If you are buying a Windows laptop, be aware that Vista is slower than Windows XP, in my experience, and still has compatibility issues with add-on hardware and software. If you’d prefer to stick with XP, you will find that many fewer models are available with it. And Microsoft has decreed that after June 30, mainstream, name-brand laptops will no longer come pre-equipped with XP.

Video: I recommend getting an LED-powered screen, which is brighter and saves power. Also, if you are choosing Vista, or if you do a lot of converting video for use on portable devices, consider getting a laptop with a separate video card inside that has its own memory.

Memory: If you’re buying an Apple laptop, two gigabytes of memory is plenty. If you’re using Vista Home Premium, I’d consider three gigabytes for best performance.

Processor: Any dual-core processor will be fine. Don’t pay a penny extra for faster processor speed.

Storage: In a mainstream laptop that will be your main computer, look for a 160-gigabyte hard disk or larger. A new kind of storage, called SSD, or solid state disk, is now available. But it is still way too costly for most users, and at the moment is available only in smaller capacities.

Battery life: Many laptops today rarely spend time away from an electrical outlet. But if yours will, look for a battery life of at least three hours between charges.

Wireless: Make sure your new laptop has the new, faster “N” version of Wi-Fi built in. Many cheaper laptops don’t. You can also get a cellphone modem built in, but they are costly and carry a monthly fee. You can always add an external cellphone modem later.

Other features: A built-in camera and microphone can be quite useful, and so can a feature on some Windows machines that allows you to play music and videos without fully booting up the computer.

Don’t let yourself be swayed by sales pitches, or by fanaticism for or against Windows or the Mac. Think hard about how you use your computer and what your budget will allow, and stick to those priorities.

• 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.

There are two models for this legal Internet distribution. Some shows and movies can be purchased or rented from services like Apple’s iTunes or Amazon’s Unbox. You pay a fee for these downloads, which don’t have commercials, and you can keep any videos you buy to watch repeatedly even without an Internet connection.

The other model, common on the Web sites of the TV networks, is free, ad-supported streaming directly within a Web browser. In this approach, you pay nothing, but you have to watch commercials that can’t be skipped. You must be connected to the Internet while watching, and you don’t get to keep the video.

This week, the ad-supported, streaming approach took a big leap forward with the launch of a Hollywood-backed service called Hulu, at hulu.com. Hulu aims to be a legal, one-stop shop for streaming of TV shows and movies from numerous networks and studios. It’s intended as an attractive antidote to pirate sites and to Google’s YouTube service, which has angered the media companies by allowing users to post all or parts of movies and TV shows without permission or payment.

Hulu is a joint effort of two big media conglomerates, NBC Universal and News Corp., each of which operates multiple networks and studios. (News Corp. also owns The Wall Street Journal and the Web sites where this column is published.) But Hulu contains programming from other companies as well, including Sony and Time Warner. All told, it offers full episodes or clips from about 400 TV series, plus 100 feature films.

I’ve been testing Hulu, and I am very impressed with its design and ease of use, and with the fact that it allows users to edit and re-publish its content on their own sites. Despite some drawbacks, it’s the first Web property I’ve seen from mainstream studios or networks that shows a real understanding of both modern Web design and the Internet’s culture of sharing. In my view, it’s far better than the typical network or studio Web site.

Even though Hulu lacks programming from ABC, CBS and many cable networks, it has a fair selection of popular shows, such as “30 Rock,” “The Office,” “The Simpsons,” “Battlestar Galactica” and “Saturday Night Live.” Its movie catalog includes old favorites like “The Usual Suspects,” “The Big Lebowski” and “Sideways.”

The site is organized in a clean, elegant manner. You can browse shows alphabetically, by genre or by network, or you can use an excellent search system. The search system even brings up links to videos of shows on other sites, such as ABC’s “Grey’s Anatomy,” that are missing from Hulu’s own collection.

Watching the material is a pleasure. You can view it in a fixed window or in full-screen view. You can also “pop out” the viewing window so you can place it anywhere on your screen and resize it to your liking. A feature called “lower lights” grays out everything on the computer screen but the video itself.

Even the advertising is relatively painless. TV shows contain just 25% of the commercial time that’s on regular TV. And Hulu allows you, in some cases, to choose the advertisers whose commercials you see, or else to opt to watch a movie trailer at the start of a video in exchange for seeing no further ads during that viewing.

In a break with Hollywood’s past rigidity, Hulu makes it easy to share, even edit, shows and clips. You can repost an entire video, or any portion of it, on your own blog or on social networking sites.

But Hulu also has some major downsides. Most important, Hulu lacks depth. Even with TV series from its owners’ own networks, Hulu typically contains only a small number of full-length episodes, and mainly offers short clips. In some cases, episodes expire after a while. For some shows, such as “Saturday Night Live,” there aren’t any full episodes, only clips. And the wildly popular “American Idol” isn’t in Hulu at all, even though it airs on News Corp.’s Fox network.

This stands in stark contrast to the depth offered on iTunes, where you can find multiple seasons of full episodes of many shows. And it doesn’t begin to compete with pirate sites, where you can find nearly everything.

Also, Hulu requires a decent broadband connection — a speed of at least 1 megabit per second is recommended, and even higher speeds are needed for some content. That means that using Hulu over the slowest DSL lines or cellphone modem cards will likely provide a poor experience.

Another problem is that, unlike iTunes or Amazon Unbox, Hulu can’t be used via a TV set-top box or a portable player. And shows can’t be saved for offline viewing, such as during flights.

Still, Hulu is a good start for Hollywood in finally providing a better experience for Internet streaming of TV and movies. If the service can add a lot more content and make viewing possible in more scenarios, it might strike a real blow against piracy.

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.

Many others keep their landline-phone service grudgingly, only because it is needed for things like fax machines. But even they often use their cellphones at home, because their friends and family members dial their cellphone number routinely, and their personal phone books are inside their cellphones.

But there is a big drawback to using a cellphone at home, especially in a large house: You have to schlep it around with you from room to room. By contrast, landline phone service can be used via either cordless or corded extension phones. Now, T-Mobile, one of the big U.S. cellphone companies, is rolling out a new system that it hopes will make cellphone service at home more convenient and even cheaper to use.

The service, being introduced this month in two test cities, Seattle and Dallas, allows you to use a cellphone account with any corded or cordless home phone, with multiple extensions, for just $10 a month. That very low price gets you unlimited domestic calls.

This new T-Mobile service, tentatively called Talk Forever Home Phone, is likely to be available nationally in a few months. It works via a special Wi-Fi wireless router that you must buy, with a two-year contract, for a one-time charge of $50. The router, which can either replace or supplement your existing wireless router, is essentially a stationary cellphone that marries an in-home Wi-Fi network to the T-Mobile cellphone network.

I have been testing the new system and found that it worked well, and it was extremely simple to set up and use. For my tests, I used a cordless phone supplied by T-Mobile, which included a base station and one extension handset. I was able to make and receive calls all over my home in exactly the same manner, and with exactly the same quality, as I do with my normal cordless landline service.

While T-Mobile is selling this cordless phone as a $60 option, it isn’t necessary for use with the new $10 service. The only new hardware that is required is the special Wi-Fi router.

However, there are some significant downsides to the new T-Mobile service that might make people think twice about dumping their landlines. For one thing, it doesn’t work with fax machines, home-security systems and other devices that rely on dial-up modems. Also, unlike landline phones, it doesn’t automatically transmit your home address to 911 emergency centers. You have to manually supply that address to T-Mobile during signup, and the company then sends it to your local emergency center.

Another downside: You must be a T-Mobile cellphone customer to buy and use this $10 monthly home service, and your T-Mobile plan must either be an individual plan costing at least $40 a month or a family plan costing at least $50 a month.

Finally, while you can transfer your current landline phone number to this new service, it cannot share your existing T-Mobile cellphone number. So people who are used to calling you on your cellphone will still do so, and you will still have to race for the cellphone or carry it around to receive those calls. You also can’t transfer your cellphone’s address book to the new home phone.

The special router is made by Linksys and looks very much like a typical Linksys router, except for the fact that it has two standard telephone jacks in the back and slots inside for T-Mobile SIM cards, the same kind that are inside a T-Mobile cellphone.

You can use the special router as a replacement for your current Wi-Fi router, but I just plugged it into an existing port on my old router, inserted the SIM card, and then plugged the cordless-phone base station into one of the phone jacks. It worked immediately, and didn’t affect or degrade my existing Internet service.

In addition to enabling the phone service around my house, the router was also usable by my computers for Internet connectivity, though it doesn’t support the new, fast “n” flavor of Wi-Fi.

This new system is not a so-called voice-over-Internet-protocol phone system, such as Vonage. It doesn’t carry your phone calls wholly over the Internet, but merely uses the Internet to get them to the T-Mobile cellphone network, which then carries the calls as if they had been made on a cellphone.

T-Mobile says the system will work fine even if you don’t have T-Mobile cellphone coverage at your house, because the call doesn’t rely on the cellphone network for its first leg and only is routed to the cell network once it reaches a T-Mobile switching center.

If you are a T-Mobile customer and can live with this system’s drawbacks, the $10 monthly fee may be hard to resist. But this new system is far from a perfect replacement for landline phones.

• 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.

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.

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.