Linux on netbooks isn’t going away though. In fact, software and hardware companies have been making big investments to improve Linux netbooks. For the past week, I’ve been using several flavors of Linux running on netbooks — Ubuntu, Hewlett-Packard’s Mi (which is based on Ubuntu) and Moblin, created largely by Intel and not yet available commercially. In all cases, the Linux netbooks failed at some basic functions that any laptop, no matter how tiny and inexpensive, should be able to handle, like working with printers. At the same time, Mi and Moblin have impressive graphical user interfaces well-suited to the habits of typical netbook users, like checking email and accessing social-networking sites, as well as the small screens and low horsepower of tiny laptops. In addition to Linux, all of the computers shared the standard features, or lack thereof, common among netbooks, including compact keyboards and no DVD drives.

H-P’s Mini 110 Mi Edition

The most polished of the products was H-P’s Mini 110 Mi Edition, a new model with a 10.1-inch screen that H-P will begin selling on its Web site for $279.99 on June 10. That’s nearly $50 less than what H-P will charge for the Mini 110 running Windows XP, which will come with a 160-gigabyte hard drive instead of the 8-gigabyte solid-state drive that will come with the Mi edition.

The striking thing about this netbook is the slick graphical user interface created by H-P that runs on top of Ubuntu and first began appearing on H-P netbooks early this year. Instead of a traditional desktop like that found in Windows and the Mac, Mi (pronounced “me”) arranges commonly used applications and content on a screen called the “dashboard,” which looks like a personalized Web page and lists recently received emails, fresh thumbnail images of favorite Web sites, and a Web-search toolbar.

The Mi home screen is a clever way to make the computer seem alive with on- and off-line content, which is fitting since netbooks are designed for on-the-go Internet activities. It’s also tailor-made for the small screen size of netbooks.

A more eye-catching iteration of Linux is Moblin, which I tried out in test form on an Acer netbook; it is expected to ship on netbooks by the end of the year. Moblin has a menu of icons at the top of the screen, the most interesting of which leads to the M-Zone, a home screen that displays calendar appointments and favorite applications alongside snapshots of recently visited sites and a continuous feed from the user’s Twitter network.

An icon called “People” leads to a list of instant-messaging buddies, while another, called “Zones,” let me organize all the applications I had launched into different virtual workspaces, which is useful for hopping between various tasks on a small-screen device like a netbook.

The look and feel of the standard Ubuntu system, without the Mi interface, is more commonplace. I tried out a Dell Mini 10 with a 10.1-inch display and 160-gigabyte hard drive that sells for $349 on Dell’s Web site. The Mini 10 ships with version 8.04 of Ubuntu, which resembles Windows XP, with its desktop, taskbar and pop-up menu system. Ubuntu, in some cases, seemed to overestimate the size of the Dell Mini’s display: A window for configuring wireless-networking capabilities was so large it bled off the screen, and I couldn’t access all the buttons on it. I also installed on the Dell a new version of Ubuntu Netbook Remix, which works better on small screens. Since a Windows XP version of the Dell Mini 10 sells for the same price as the Ubuntu, I can’t see a compelling reason to choose the Ubuntu option.

All the netbooks I tried had compatibility problems with other external devices. The netbooks couldn’t load the software drivers to let me print to my Canon and Dell printers. I couldn’t load pictures over a USB cable from my Canon PowerShot SD750 digital camera. I was able to get my pictures on the machines by plugging a storage card from my camera directly into the netbooks.

Canonical, the London company that oversees development work on Ubuntu, says it is improving the system’s compatibility with various devices. Intel says it is unfair to judge Moblin until it is commercially available.

Some key applications currently don’t run on Linux, like Apple’s iTunes, which makes it difficult to load music files onto iPods from the netbooks. While the Linux laptops didn’t run Microsoft Office, they came with OpenOffice, a free package of word-processing, spreadsheet and presentation applications that allowed me to open and modify basic Word and Excel files.

The companies behind Linux netbooks have made great strides in improving user interfaces, but until they can achieve similar breakthroughs in how the machines work with other devices, Windows netbooks are still a better deal.

• Email nick.wingfield@wsj.com. Walter S. Mossberg is away and will return next Thursday.

So, I have steered away from recommending Linux, the free computer operating system that is the darling of many techies and IT managers, and a challenger to Microsoft’s dominant Windows and Apple’s resurgent Macintosh operating system, OS X. Linux, which runs on the same hardware as Windows, has always required much more technical expertise and a yen for tinkering than average users possess.

Lately, however, I’ve received a steady stream of emails from readers urging me to take a look at a variant of Linux called Ubuntu, which, these folks claimed, is finally polished enough for a mainstream user to handle. My interest increased when Dell began to sell a few computer models preloaded with Ubuntu instead of Windows.

I’ve been testing one of those Dell Ubuntu computers, a laptop called the Inspiron 1420N. I evaluated it strictly from the point of view of an average user, someone who wouldn’t want to enter text commands, hunt the Web for drivers and enabling software, or learn a whole new user interface. I focused on Ubuntu and the software programs that come bundled with it, not on the hardware, which is a pretty typical Dell laptop.

My verdict: Even in the relatively slick Ubuntu variation, Linux is still too rough around the edges for the vast majority of computer users. While Ubuntu looks a lot like Windows or Mac OS X, it is full of little complications and hassles that will quickly frustrate most people who just want to use their computers, not maintain or tweak them.

Before every passionate Linux fan attacks that conclusion, let me note that even the folks who make and sell Ubuntu agree with it. Mark Shuttleworth, the South African-born founder of the Ubuntu project, told me this week that “it would be reasonable to say that this is not ready for the mass market.” And Dell’s Web site for its Ubuntu computers warns that these machines are for “for advanced users and tech enthusiasts.”

So, what do I mean when I say Ubuntu is too rough around the edges for average users? Here are some examples.

There is no control panel for adjusting the way the touch pad works, and I found it so sensitive that I was constantly launching programs and opening windows accidentally by touching the thing. Every time the computer awoke from sleep, the volume control software crashed and had to be reloaded.

When I tried to play common audio and video files, such as MP3 songs, I was told I had to first download special files called codecs that are built into Windows and Mac computers. I was warned that some of these codecs might be “bad” or “ugly.”

To get the computer to recognize my Kodak camera and Apple iPod, I had to reboot it several times. When it did find the iPod, it wasn’t able to synchronize with it. Playing videos was a bad experience, with lots of flickering and freezing. Oh, and there’s no built-in software for playing commercial DVDs.

The Ubuntu-equipped Inspiron 1420N starts at $744, but the configuration that Dell lent me for testing sells for $1,415. The same unit equipped with Windows Vista costs $1,524. The Ubuntu version includes OpenOffice, the free office suite that competes with Microsoft Office. Dell charges an added $149 for Microsoft Office.

Ubuntu and other versions of Linux have several advantages. Unlike Windows and OS X, they’re free. Unlike Mac OS X, they can be run on the least-expensive popular hardware configurations. Unlike Windows, but like the Mac, they are essentially free of viruses and spyware. And unlike Windows and Mac OS X, they are built and constantly improved by a world-wide network of developers, professional and amateur — the so-called open-source concept that produced the excellent Firefox Web browser.

It makes sense that all the best software brains can’t be located in just two places: Redmond, Wash., where Microsoft is based, and Cupertino, Calif., Apple’s base. And plenty of people reading this have had lots of frustrations with the two better-known operating systems, especially Windows, whose latest iteration, Vista, is disappointing in many ways.

But open source is a two-edged sword. While it draws on smart developers from many places, nobody is ultimately responsible for the quality of the product, and open-source developers often have an imperfect feel for how average people use software. A European company called Canonical is the “commercial sponsor” of Ubuntu and provides support. But it’s largely focused on corporate and techie users. Average Ubuntu users are likely to have to wade through online forums, often written in technical language, to get help.

Dell and Canonical tell me there are complex workarounds for some of the problems I encountered, and that built-in improvements are planned for others. But for now, I still advise mainstream, nontechnical users to avoid Linux.

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.