Too often, security programs significantly slow down the computer, causing lags in booting up the machine, launching programs and receiving email. Not only that, they can be incredibly annoying, popping up frequent messages or asking questions in techie lingo.

The main screen of the 2009 version of Norton Internet Security is streamlined and even includes a gauge to show much drain the security program is placing on the computer.

Now, Symantec (SYMC) has decided to radically rewrite its main security suite for Windows to directly address these problems. And in my tests, this new product, Norton Internet Security 2009, largely succeeded. It isn’t perfect, but it is the fastest, simplest and least obtrusive security suite I have ever used.

Being quick and quiet is great, but, of course, a security product also has to be effective against the vast number of viruses, spyware programs and other malicious attacks aimed at Windows. I don’t have a security lab in which to test such effectiveness. But PC Magazine does, and the magazine called the new Norton suite’s spyware and virus protection “extremely effective.” The magazine’s tests are described at http://www.pcmag.com/article2/0,2817,2330024,00.asp.

However, I wasn’t impressed with Norton’s optional antispam feature, which caused the only significant problem I ran into in my testing.

The new suite costs $70, and can be purchased at symantec.com and elsewhere. For that price, you get to install it on three PCs and you get a one-year subscription to its updates, which cost $60 thereafter.

Symantec is now including free support, even over the phone, though in my tests this support proved lousy. Norton Internet Security 2009 works only on Windows XP and Windows Vista.

I tested the new security suite on a Dell (DELL) desktop running Vista and on a Macintosh laptop running Windows XP as a “virtual machine,” meaning Windows and Windows programs ran simultaneously with the Mac operating system. Symantec assured me the program would run properly in this latter setup, and I had run the previous version of Norton successfully in the same environment.

The first thing you notice about NIS 2009 is the fast and simple installation. The process took under two minutes on each of my test machines.

File scanning is also much faster, partly because the new suite has a feature called Insight that allows it to skip the scanning and rescanning of many of your files. Insight gathers information about your installed programs and compares them against a list of programs Symantec knows are “trusted,” through either its own research or through scanning results voluntarily submitted by other users. These trusted programs are then exempted from future scans, saving a ton of time.

The new Norton suite has a feature called Insight which calculates how many of your programs it knows are trusted, and therefore needn’t be scanned repeatedly, saving time.

For instance, on my Dell running Vista, an immediate complete scan done before Insight analyzed the computer took more than an hour. But after Insight determined that over 70% of my programs were trusted, complete scans took 10 minutes or less. Of course, your data files, like Word documents and emails, still must be scanned, because they are typically unique.

To minimize the impact on users, the new Norton does scanning and other tasks only when it detects that the computer has been idle for at least 10 minutes. And new virus definitions trickle into your computer invisibly, in the background, rather than all at once in a major process.

Symantec is so certain that its product has a low impact on PC performance that it built a gauge into its new streamlined main screen that shows its drain on the main processor, or CPU.

NIS 2009 is also far less annoying than other suites I’ve used. In normal operation, it notifies you only when it has completed a background task or if there’s a threat or a repair that requires a user action, such as a reboot. And there’s an even quieter optional “silent mode” that can turn off nearly every nonurgent activity of Norton for up to six hours. Silent Mode is automatically activated during full-screen activities, such as playing games or watching movies.

The new suite has a bunch of other features, including a browser toolbar for Internet Explorer and Firefox that warns against fake and malicious Web pages, and that can securely enter your passwords and other information on Web sites. It also has an antispam feature for Microsoft (MSFT) Outlook and Outlook Express.

This antispam feature, which is off by default, was rated as weak by PC Magazine and, in my tests, it caused both Norton and Outlook Express to crash repeatedly in Windows XP running on my Mac. Symantec suspects this is a problem particular to running Windows the way I was on the Mac. After I reinstalled Norton and turned off the feature, all was well again.

But Symantec’s free tech-support service was not only unable to diagnose the problem, it didn’t even know the difference between Outlook and Outlook Express.

Despite this one glitch, I can recommend Norton Internet Security 2009 as a good way to protect your Windows computer with minimal impact on your time and attention.

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.

These types of attacks are called “social engineering,” and they are used by criminals to steal your money and identity, and to plant on your computer malicious software that can be used to keep ripping you off. Social engineering is the online equivalent of an old-fashioned con game, in which a crook frightens people with false warnings, or tempts them with false promises, and then robs them.

While viruses and spyware overwhelmingly afflict Microsoft’s (MSFT) Windows users and spare users of Apple’s (AAPL) Macintosh computers, social-engineering schemes can ensnare Mac users as well. There’s nothing inherent in Macs that makes their owners more resistant to falling for social-engineering scams.

The most common form of social engineering is called phishing, a one-two punch using both email and Web browsing to trick people into typing confidential information into Web sites that look like the sites of real companies, especially financial institutions. But these phishing sites are actually skillfully designed fakes that transmit your sensitive data to criminals, often in distant countries. Once these creeps have your passwords and account numbers, they can loot your funds and steal your identity.

Here are some tips to help you avoid being the victim of social engineering, updated from a similar column I wrote in 2006. It includes information on some antiphishing software that wasn’t available back then. But remember: Security software alone can’t save you from scams.

1. Never, ever click on a link embedded in an email that appears to come from a financial institution, even if it’s your own bank or brokerage and even if it looks official right down to the logo. The same goes for payment or auction services, like PayPal or eBay (EBAY). Don’t do this even if the email asserts that your account has a problem, or that the bank has to verify your information. And certainly don’t enter any passwords, Social Security numbers or account numbers directly in an email.

These types of emails are almost always fakes, and the links they contain almost always lead to phony Web sites run by criminals. The only exception might be a confirmation email from a brokerage firm concerning a trade you know you made minutes before. Even legitimate-looking addresses in emails or in the address bar of Web browsers can be fakes that hide the crooks’ true Web addresses. The lock icon on a Web site can also be falsified.

If you are truly worried about your account, call the bank or company, or go to its Web site by manually typing in its address or by using a well-established bookmark in your browser that you created yourself.

2. Don’t click on links to offers for free software or goods that you receive in an email, especially from a sender or company you’ve never heard of.

3. Never download software from unfamiliar Web sites unless you are absolutely sure you need it and it’s legitimate. Even if it claims to be a useful program, it may very well be a malicious application like a “key logger,” which can report back to crooks everything you type into your computer. If you really want the program, do a Web search on it first, to see if others have reported it as a malicious fake.

4. If a Web site tells you that you need to download special viewing software to see its videos, don’t do it. Even if it claims to be giving you legitimate viewing software, like Microsoft’s Silverlight, Adobe’s (ADBE) Flash or Apple’s QuickTime, don’t download it there. Go to the official Microsoft, Adobe or Apple Web sites to get these viewers.

5. Use a Web browser, like Internet Explorer 7 on Windows, or Firefox 2.0 on Windows or Mac, that includes built-in features to warn you about, or block access to, known phishing sites. The next versions of these two browsers will have even stronger features that will detect sites that are not only fake, but which are known to distribute malicious software.

Unfortunately, the third major browser, Apple’s otherwise excellent Safari for Mac and Windows, lacks any such antiphishing detection, though I expect Apple to add the feature in a future version. So, for now, Mac users worried about phishing should rely on Firefox.

6. Consider security software that tries to detect and block phishing sites. McAfee’s (MFE) free Site Advisor and paid Site Advisor Plus products do a good job. Symantec (SYMC) has similar features built into its large security suites, Norton 360 2.0 and Norton Internet Security 2008.

7. Educate yourself by reading about social engineering and phishing and how to avoid being a victim. Microsoft has a very good guide at: microsoft.com/protect/yourself/phishing/identify.mspx and Symantec has one at: symantec.com/norton/clubsymantec/library/article.jsp?aid=cs_phishing.

Follow these tips and you’ll be a happier — and safer — surfer.

Find all of Walt Mossberg’s columns and videos online, free, at the new All Things Digital Web site, http://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.

Back in January, when I reviewed the massive new operating system, which took more than five years to develop, I called it “unexciting” because many of the breakthrough features Microsoft had planned for it had been jettisoned, and most of the rest were already present in the rival Apple Macintosh operating system, OS X.

But I also said it was “worthy,” and better than prior versions of Windows, because it has a stronger security system under the hood and better integrated searching.

Over the ensuing months, however, Vista has proved to be a disappointment, even though Microsoft says it’s selling like hotcakes. Based on my own experience and on reports from readers, it’s clear that many Vista PCs start up more slowly than new PCs running its predecessor, Windows XP, or than even well-worn Macs. And there is still a significant compatibility problem: Too many software and hardware products still don’t run, or don’t run properly, with Vista.

So, if you’re shopping for a new Windows computer, one of your first decisions is whether you want to get Vista, which comes on almost all new models, or to stick with Windows XP. PC makers are still offering XP on a few new consumer PCs. For instance, Dell offers four consumer laptops and two consumer desktops that can be ordered with XP.

Buying XP will likely result in fewer frustrations in the short run. But buying Vista may be the better choice for the long run. Over time, more and more products will be released that are tailored to the new system.

Your other option is to shun the Windows dilemma and buy a Macintosh. I regard the Mac operating system as superior to Windows, and Apple embeds it in beautifully designed machines. Macs have been spared the plague of viruses and spyware that afflicts Windows, and have better built-in multimedia software.

But, if you’re thinking of buying a Mac, it makes sense to wait a few weeks or months to gauge the early reviews and user reactions to Apple’s own new version of its operating system, called Leopard, due out Oct. 26. After that date, Apple won’t build in the current version of OS X, called Tiger, on new machines.

Here are some tips if you’re shopping for a new Windows PC this fall. They apply to desktop PCs and to most mainstream laptops, though there are additional considerations, such as size and weight and battery life, for smaller laptops meant primarily for travel. As always, these recommendations are intended for average consumers doing average tasks, not for heavy gamers, video professionals, or corporate buyers.

Operating system: If you opt for Vista, the best choice for average consumers is a version called Home Premium, which includes all of the new graphics and multimedia features. Many low-end PCs have only a stripped-down version called Home Basic. Some people may need Vista Business, a version that can link to some kinds of corporate networks that the two Home varieties can’t. If your budget allows, you can get an expensive version called Ultimate that includes the features of both the Home and Business versions.

Junk software: Most Windows consumer models are stuffed with “craplets” — crippled trial versions of programs. They take up space and can slow down the machine. One way to avoid these is to buy a so-called business PC, like one of Dell’s new Vostro models. Dell also allows you to opt out of trial software, especially when ordering its pricier XPS models. Many other manufacturers make this hard or impossible, especially if you buy a PC at a retail store. But the stores may clean up a new PC for a fee.

Memory: Buy at least one gigabyte of memory for Home Basic and at least two gigabytes for all other Vista versions.

Video: Vista’s flashy graphical interface works best with a separate, or “discrete,” graphics card that has its own memory. Some “integrated” graphics systems work fine, too, but they claim some of your main memory via an approach called shared memory.

Processor: Any “dual-core” processor from Intel or AMD should be fine for Vista. Don’t worry about processor speed. Buying added memory does more for performance.

Hard drive: Don’t scrimp on storage space, unless you are absolutely certain you won’t be saving many photos, songs or videos. Even an average PC should come with 300 gigabytes of hard-disk space for a reasonable price.

Performance: If you’re shopping in a retail store, try to check the performance rating Microsoft builds into Vista. It’s available by clicking “Show more details” in Vista’s “Welcome Center” screen. If this rating is below 3.0 on a Home Premium model, avoid the computer. For best results, shoot for 3.5 or higher.

Price: You can get a bargain-basement computer for under $400. But, for a versatile Vista PC with Home Premium, two gigabytes of memory, discrete video, a large hard disk and a dual-core processor, you should expect to spend $800 or more.

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.

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.

It gets better. This new PC, called Zonbu, from a new company of the same name, automatically receives free updates of its software when new versions come out. It doesn’t require antivirus or other security programs because it runs on the Linux operating system, which has attracted very few viruses or spyware programs. And it takes up almost no room — it’s a tiny little box.

Zonbu’s overall goal is to vastly simplify the process of buying and using a computer. The idea is to make it not only more affordable, but also much less of a hassle and much more energy efficient.

I’ve been testing the Zonbu, and it does work. Its software is still in beta, or test, mode until next month. But you can buy it right now at Zonbu.com with free software updates into the future. However, there’s a catch — several catches, in fact. Some have to do with the machine’s design and pricing, and others with its performance. Taken together, they prevent me from recommending this computer, despite its intriguing price and concept.

The biggest catch is that the Zonbu computer doesn’t include a hard disk for storing files (that’s one reason it uses so little energy). Instead, all of your files are stored online on the company’s servers. That offers several advantages, such as the fact that the files are automatically backed up.

But you have to pay for that online storage. In fact, to get the $99 price for the Zonbu computer, you have to commit to a two-year contract at prices ranging from $12.95 a month for a relatively small 25 gigabytes of storage to $19.95 a month for 100 gigabytes. If you opt to pay month to month instead of two years in advance, the Zonbu will cost you $249.

To get the Zonbu for $99 with 100 gig-abytes of storage, it will cost you $517.95 up-front after the discount of three free months that the company is currently offering. And the Zonbu doesn’t come with a monitor, keyboard, mouse, Wi-Fi adapter, speakers or DVD drive.

By comparison, you can get a Dell Inspiron 531s for just $529, after rebate. It has twice the memory, a DVD drive and a much better processor than the Zonbu. And it comes with a screen, keyboard, speakers and mouse — oh, and a 160-gigabyte hard disk that requires no monthly fee.

To be fair, the Dell doesn’t come with a full-fledged office productivity suite, while the Zonbu has OpenOffice, a competitor to Microsoft Office, preloaded. To get OpenOffice on the Dell, you must download and install it.

Also, the Zonbu monthly service fee is offset by some savings. The $99 machine uses so much less energy than a typical PC that the company claims you could save noticeably on your electric bill. And you might also save the cost of subscribing to security software updates.

Zonbu

Because the Zonbu stores your files on a remote server, you can also use them remotely, at no extra cost, from another Zonbu or from any Windows PC.

To speed things up — and guard against an Internet service outage — the built-in programs are stored locally on the computer, and Zonbu includes a small 4 gigabyte memory card in the machine to cache your documents. In my tests, this allowed me to keep using the Zonbu even when I unplugged it from the Internet.

In addition to OpenOffice, the Zonbu comes with the Firefox Web browser, an Outlook clone called Evolution, an iTunes clone called Banshee, the Skype Internet phone software, and a bunch of other programs for organizing photos, playing video and more. There are also some casual games.

To Zonbu’s credit, the machine is capable of recognizing lots of printers and digital cameras, out of the box. It worked well with my Kodak camera and Hewlett-Packard printer.

But there are three other big problems with the Zonbu, problems that belie its goal of eliminating hassles. First, you aren’t allowed to install any added software. You’re stuck with what the company provides. And that means, for instance, no video-editing software, for now at least.

Second, a lot of this Linux software is rough, below the polished level of Windows or Mac programs. In my tests, various programs crashed or froze frequently. While the Banshee program is supposed to work with iPods, it failed to work properly with both of the iPods I tested.

Finally, I found that the Zonbu crawled much of the time. Folders took forever to open, email took way too long to appear, and so forth. And I was testing it on a very fast Internet connection. This may be because of the very wimpy processor Zonbu uses to save money and energy.

I strongly support Zonbu’s goals of making computing simpler, cheaper and more energy efficient. But this product has too many compromises.

• 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.