I saw your recent review of ICE, the emergency medical information app for the iPhone. But my iPhone is set up to require a passcode to get to the home screen and run apps. Is there any way to display emergency contacts before a person enters the passcode?

There are some apps that allow you to customize the wallpaper of your iPhone or iPod Touch by adding a few lines of text that can be seen before it’s unlocked. One, called Close Call, displays a red cross and, next to it, an emergency phone number, and one brief line about, say, a key allergy or medical condition. The app is free, and is from a company called Polka, at polka.com.

I installed VMware Fusion on my Mac so I can run a virtual Windows XP computer on the Mac. When in the virtual Windows environment, I use security software. If I have the Fusion program shut down completely when I am not using it, will my computer be vulnerable to Windows security threats?

The vast majority of viruses, spyware and other malicious software is designed to run on Windows and cannot run natively on the Mac’s built-in operating system. So, while you are wise to use security software in your virtual Windows PC, any malware it misses won’t be able to run when Fusion is shut down. While even a virtual PC can get real viruses, this faux PC just disappears when Fusion is shut down, and so does all its software, including viruses.

But simply because Windows-based malware can’t run on the Mac’s OS, that doesn’t mean you don’t have to be careful. You can still be tricked by false email and Web sites into giving up personal information.

• You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

Should I install Microsoft’s “SP3″ upgrade to Windows XP? I hear opinions on both sides.

In general, I recommend this upgrade, officially called Service Pack 3, because it beefs up security, and that helps not only you, but all Windows users, to avoid the spread of malicious software. If your PC is more secure, it is less likely to be used as a source from which other PCs can be infected.

I have upgraded a couple of XP PCs to SP3 without any downside. However, like you, I have also heard from some users that the upgrade caused them problems.

As with any major operating-system upgrade, either outcome can occur, depending upon your computer’s particular configuration and condition. So, if you’re on the fence, consider your level of concern about security.

How do cellular data cards compare with fast cable modems in terms of Internet speed? Are these cards more secure than Wi-Fi?

In my experience, using and testing cellular data cards on various laptops, they typically deliver, in real day-to-day use, somewhere between 300 kilobits per second and 1.5 megabits per second. By contrast, a fast cable Internet service can actually deliver up to 16 mbps. So cable is much faster.

Your security question is much more complicated. Wi-Fi security can range from very poor to quite good. It depends on where and how you use Wi-Fi, how you or others have set up the wireless network, and how you have configured your own computer.

Accessing the Internet over a cellular network is a more controlled process, because the cellphone-network operator manages the transmission, and in most cases supplies and configures the software on your computer. So, it is likely to be safer than the worst Wi-Fi setups. But I would never suggest that cellular data card transmissions are invulnerable to hackers or criminals.

What’s the difference between file-based backup and image-based backup software? Why would I choose one over the other?

Image-based backup software copies an image of your entire hard-disk, including all the programs, settings and obscure files that you never see. While it can be used to recover individual files, in some cases, it is mainly designed to allow you to restore your entire hard disk in the event that you lose it all.

File-based backup software, which is more common among consumers, is typically designed to preserve a copy of only your personal data, the material you can’t re-purchase or re-install if your hard disk dies.

That includes word-processing files, spreadsheets, presentations, emails, contacts, calendar items, photos and other items you created. It also is often used to back up music and video files that would be time-consuming, or very expensive, to re-acquire. And in some cases, it can preserve settings and preferences, such as Web bookmarks.

Both types of backup generally begin with a time-consuming initial session, followed by shorter sessions to update the backup with incremental changes.

Many people choose file-based backup because it occupies less space, and is generally quicker and also less expensive. Image-based backup is for folks who are willing to spend the added money and time to be sure they can restore their whole computer, or clone its contents completely to another machine.

• You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

Is there a way to transfer a Windows Media music file to iTunes?

If the Windows Media file is copy-protected, typically because you bought it from an online store that copy-protects its music, iTunes cannot import or play it. However, if it is unprotected, which is typical for files you created from your own CDs using Windows Media Player, iTunes can import the file and automatically convert it into a format it can use.

I would like to purchase an iPhone, but run it on the Verizon network. I realize that AT&T has an exclusive at this time, but is there a way to do this on the secondary market?

No. The radio inside the iPhone is incompatible with the network technology used by Verizon and Sprint. That cannot be changed by hacking the software, or replacing the SIM card in the phone.

I need to buy a new laptop computer and am wondering if you think Vista is wise at this point or should I still stick with Windows XP if I can find it? I only do emails, browsing the net and some downloading of music and photos. I am retired and don’t know much about computers.

Vista easily handles the tasks you want to do, but it will require heftier hardware to work at acceptable speeds, and, assuming you are used to working with XP, Vista will require you to learn some new things. If you buy XP, you can get away with a more modestly equipped computer, and you will be working with a more familiar interface. So, in your particular situation, I would suggest an XP machine. But I urge you to make sure it gets upgraded to the latest revision, called SP3, which bolsters the security of XP, so it is closer to that of Vista. Depending on your setup, this upgrade may be delivered automatically by Microsoft, but you may have to agree to accept it.

You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

In the new version of Microsoft Office, I cannot find a “favorites” capability in the Open dialog box. In my older version, when I began to open a document, I had a box on the left called “Favorites” that I could invoke to find common file locations. Did they really kill this very useful feature?

No, but they changed the way you make it visible in Office 2007. You can get back your “Favorites” category by right-clicking the bar at the left-hand side of the Open dialog. From the menu that appears, click on “Add Favorites,” and your Favorites category should appear in the left-hand bar, and stay there.

If I have McAfee security software, do I need an antispyware program as well?

Everyone running a Windows computer, even a virtual Windows computer on a Mac, should have antispyware software. In some ways, spyware is a worse security problem than viruses, and can lead to identity theft.

McAfee has made many types and versions of security software over the years. Some, especially recent versions of the company’s comprehensive products, include antispyware protection. Check your version to make sure it includes this capability. If it doesn’t, you will either need to upgrade to a more comprehensive suite, or obtain a separate anti-spyware product.

When my friend put a Spike Jones CD of mine into his Mac to import it using iTunes, the CD was misidentified with an embarrassing title. What would cause such a thing to happen? Does iTunes go out to the Web looking for album names, instead of going by what’s on a disk?

Yes. Music programs like iTunes, and all its major competitors, can’t identify a disk directly. So they rely on online databases to identify CDs. Each CD contains a hidden code that the database providers quickly match up with their huge catalogs of CDs to provide the album title, artist, date, track list and other information. But, sometimes, especially when the CD is relatively obscure, the databases are wrong and yield erroneous information. When that happens, you have to type in the information by hand.

You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

I recently lost my cellphone for a few hours. What was most upsetting was that I have nearly three years of family photos stored on my phone’s memory card. Other than emailing all of these photos to myself and then saving, is there any way you can think of how I can move these en masse (over 100 pictures) to a hard drive or disc?

Well, assuming the card is removable, you can simply remove it from the phone, pop it into your computer, and copy the pictures to the computer’s hard disk. Depending on what slots your computer has, and the type of memory card the phone uses, this might require using a cheap, small adapter for the computer.

This should work with any modern computer, Windows (MSFT) or Mac (AAPL), and no special software should be required. The memory card should show up as an external disk drive, and you would just open the folder or folders containing the images and copy them to a folder on your hard disk, as you would with any other file. You can leave the originals on the card if you wish. Alternatively, you could import the pictures using photo software like the Vista Photo Gallery or Apple’s iPhoto, although you will want to be sure that the photo software is set to save a duplicate of each photo on the hard disk.

I read your column about avoiding identity theft last week, but am still concerned. I look at my T. Rowe Price (TROW) account, my Chase account, and my J.P. Morgan (JPM) account every day. I also pay my bills online. Is it safe to do this? I am afraid someone will try to steal my passwords and get my money.

There is nothing wrong with checking your accounts and paying your bills online. Millions of people do that safely. All I was saying last week is that there are some rules you should follow to avoid falling into traps commonly set by crooks. One important rule is to never, ever trust any email you get purporting to be from a financial institution, even if it looks official. Never click on any link in any such email, or enter any login or account information in such an email.

Beyond that, just log into the sites manually or using bookmarks you created yourself. Keep your login IDs and passwords for these sites safe, either by memorizing them or writing them someplace where they won’t be easily seen or found. Choose passwords that are hard to guess, and change them every so often. I would also advise against checking financial sites or doing online banking when on public networks, especially wireless networks at hotels, coffee shops, or airports, because some crooks monitor what is typed on such networks.

What exactly was Microsoft’s thinking in moving from XP to Vista as its operating system? If it was for improved resistance to viruses and phishing, I can accept the slower operating speeds along with the few other glitches.

As with any new operating-system project, the development of Vista had numerous aims, including easier networking and an improved user interface. However, Microsoft officials at the time repeatedly said that much more robust security was the main design goal for Vista. And, in fact, Vista does have an array of security features Windows XP lacked. However, much of the antiphishing work is contained in version 7 of the Internet Explorer Web browser, which is also available to XP users. And Vista didn’t eliminate the need to operate add-on security software.

It’s also worth noting that Microsoft is continuing to bolster the security and other features of Windows XP, and will soon release a major XP update called Service Pack 3, or SP3. It includes improved security.

• You can find Mossberg’s Mailbox, and my other columns, online for free at the new All Things Digital web site, http://walt.allthingsd.com.

I want to buy a new ultralight laptop for travel. Few are available with Windows XP, which I would prefer. If I get a Vista machine, will I have compatibility issues with transferring files back and forth between it and my older laptops, both of which have XP operating systems and MS Office 2003?

Your Microsoft (MSFT) Office files, and other standard files, such as photos, songs and PDF documents, should all be compatible with both Vista and XP. While Vista has compatibility problems with some programs and some hardware, in my tests I have never found that Vista caused compatibility problems with standard, common types of files.

I plan to install Windows XP on my Apple (AAPL) iMac using Boot Camp. Whenever I am using the Windows side of the machine, I plan to shut off access to the Internet — no Web browsing or email. I even intend to unplug my wireless base station. Will this protect me from getting the Windows viruses?

Well, that’s a drastic plan, but it will probably work, since most viruses and other malicious software are acquired via email or Web sites. However, by cutting yourself off from the Internet, you may make your computer less useful while running Windows. Many programs have Internet components, and those that run locally often download new versions and features over the Internet. Plus, Microsoft distributes updates for Windows and Office using the Internet, including security fixes. For those reasons, it might be more effective to install security software on the Windows portion of your Mac and leave the Internet connection on.

I have a relatively new PC with Windows Vista. Typically, I may have five or six programs running at the same time, sometimes with multiple documents open in each one, and I like to leave my PC this way. However, I’ve noticed that every few weeks or so, Vista has an annoying tendency to restart my PC when I’m away from it, and I see a message that “Your computer was restarted to finish installing updates.” Is there any way to prevent or minimize this?

Yes. In the settings for Microsoft’s automatic update service, called Windows Update, the recommended option is to automatically download updates and install them. The second step, installing the updates, can lead to a restart. But you can change the settings to minimize or eliminate the annoyance this causes.

You can choose a specific schedule for installing the updates at a time when you won’t be interrupted. Or, you can choose an option called “Download updates but let me choose whether to install them.” A third option is called “Check for updates but let me choose whether to download and install them.” You could opt out of the update program, but that could leave your PC vulnerable to malicious software.

These options can be found by opening the Windows Security Center, then clicking on “Windows Update” at the upper left. Then, in the next window, click on “Change settings” in the left column. Similar settings are also available in Windows XP, by opening the Security Center and clicking on “Manage Security Settings for: Automatic Updates.”

• You can find Mossberg’s Mailbox, and my other columns, online for free at the new All Things Digital Web site, http://walt.allthingsd.com.

We are connected to Comcast (CMCSA) cable and use no antennas. Will we need one of the government-subsidized converter boxes next February?

Not if you are using a cable set-top box, like the vast majority of cable customers. If you are one of the minority of cable households whose TVs use an internal cable tuner, you may need a converter box. To be sure, contact your cable company or TV manufacturer.

In your laptop buying guide last week, you recommended buying a machine equipped for the “n” type Wi-Fi of wireless router. I was under the impression that this has not yet been standardized. Is that wrong?

The engineering committee that has been debating the standard for years has not yet completed its work, but the market has simply moved ahead on its own. This new, faster version of Wi-Fi is being built into routers, computers and other devices by nearly every major manufacturer. In my limited tests, I have found no compatibility problems, and it is backwards compatible with the older “g” and “b” standards.

Is the Mac immune to viruses? If not, do you have a recommendation of the type of antivirus software one should procure and load onto a Mac?

No personal computer or personal computer operating system of which I am aware is “immune” to viruses, spyware or other malicious software. That includes Apple’s (AAPL) Macintosh and its operating system, Mac OS X Leopard. Hackers have demonstrated the ability to invade the Mac. However, there are only a handful of viruses or other malicious programs for the Macintosh that have successfully spread beyond the lab. And these have harmed only a small number of actual users.

Of the well over 100,000 known viruses, spyware programs and other malicious software applications that are about in public, all but this handful are written to run on Microsoft (MSFT) Windows, and cannot operate on the Macintosh OS. For that reason, I don’t believe Macintosh owners need security software, unless they install and run Windows on their computers. If they do run Windows, Mac owners are well advised to purchase and install Windows security software to protect the Windows portion of the machine.

Having said that, I do not mean that Mac owners should be blind to security threats that don’t involve viruses or spyware. Just like Windows users, Mac users can succumb to what is called “social engineering” — scams and schemes that operate via email and Web sites that are often authored by crooks but made to look official. So, like Windows users, they must be on their guard.

You can find Mossberg’s Mailbox, and my other columns, online free at the All Things Digital web site, http://walt.allthingsd.com.

Do I need antivirus or antispyware software on a Macintosh running the Leopard operating system?

The Macintosh isn’t inherently invulnerable to malicious software. In fact, last week it was reported that there is a new scam on the Web that can plant a malicious “Trojan horse” program on the Mac. However, this is a rare event. There have been practically no viruses, spyware or other malicious programs written for the Macintosh that have actually spread outside the laboratory.

For that reason, most Mac users don’t run security software, and security software companies don’t make much of an effort to sell it for Macs. I don’t believe it is necessary, so far, for all except the most paranoid (and those who run Windows on their Macs). In fact, freedom from the burdens of running and updating security software has been one of the Mac’s big advantages.

Even the new Trojan Horse apparently relies on tricking the user, rather than on sneaking through holes in the Mac operating system. According to reports, to get infected you must go to a pornography site, and agree to download a program allegedly needed to view the porn. Next, the Mac will require that you type in your administrator ID and password to complete the installation, thus agreeing to install the program a second time. If you do all that, you get a program that supposedly redirects your Web browser to bogus Web sites. My advice: even if you frequent porn sites, don’t agree to download any programs from them (that goes for Windows users as well).

Some interpret the appearance of this new Trojan Horse as a sign that the Mac’s increasing market share will begin to attract a flood of viruses and spyware, and that Mac users will soon have to start running security software. If it happens, and the threats are more insidious than the latest one, I will be ready to change my recommendation. But not yet.

In reply to a question last week, you mentioned that there are free security programs available for Windows. Could you please suggest where to download such alternatives?

There are a number of them, but ones that I like are free, basic antivirus and antispyware programs called AVG from a company called Grisoft, which also makes more elaborate security software. You can download these programs at free.grisoft.com/doc/5390/us/frt/0.

I don’t have Microsoft PowerPoint but I occasionally get PowerPoint files as email attachments. Somewhere I read that one can download a free PowerPoint program so you can read these files. Can you help me with this, please?

I don’t know of any free versions of PowerPoint, but Microsoft does offer a free program that will let you view, but not create or edit, PowerPoint files. You can download it here.

You can find Mossberg’s Mailbox, and my other columns, online for free at the new All Things Digital Web site, http://walt.allthingsd.com.

Write to Walter S. Mossberg at mossberg@wsj.com

I currently spend about $50 to $60 per year for Norton Security software. Is this necessary when Windows XP has its own security built into the operating system?

Windows XP doesn’t include antivirus or antispyware programs, so you definitely need some sort of add-on security software. If you don’t want to pay for it, there are free alternatives available.

How do we determine when to purchase a new PC? Our current Dell is about five years old. I’m feeling a little worried because I have my music and photos on the computer and don’t want to lose them.

There’s no universal answer to your question. In general, I don’t believe people should replace computers that are working well for them just because they reach a certain age. On the other hand, five years is pretty old for a PC. At that age, the odds increase that the hard disk may develop problems, and that newer versions of the software you like will require hardware upgrades that may cost more than you want to invest in an older machine.

Assuming your Dell is working fine, that you aren’t a power user, and that your music and photo activities are simple and basic, there’s probably no urgent need to replace the PC. But, to assuage your concern about “losing” your pictures and music, you might back up those precious files to an external hard disk or an online backup service.

Last week, you compared the start-up time of Windows Vista to Apple’s new Leopard operating system, and found Vista to be much slower. But you used different laptops for each. What would the numbers be on the same Macintosh running the two operating systems?

I ran the tests again on a single computer, a fairly new Apple iMac, which can be started up, and restarted, in either Vista or Leopard. I used the Mac’s Boot Camp feature, in which only one operating system is running at a time, has its own dedicated portion of the hard disk and fully controls the hardware. The machine uses an Intel processor and other key components commonly found on Windows machines, and runs Windows just like a Dell or any standard Windows PC, without any involvement from the Mac operating system.

This Vista installation doesn’t include any of the speed-robbing trial software commonly included by PC makers, though it does have security software from Symantec. However, the test results were very similar — Leopard started and restarted much more quickly than Vista did.

In this simple test, I timed both operating systems from a cold start and a restart until the computer was fully ready for operation, with the hard disk quiet and the network connection established. The cold start, beginning with the computer completely off, took Leopard 46 seconds, but took Vista one minute and 42 seconds. A restart, beginning with the computer running an email program, the Firefox Web browser, and Microsoft Word, took one minute and two seconds for Leopard, and three minutes and 17 seconds for Vista.

You can find Mossberg’s Mailbox, and my other columns, online for free at the new All Things Digital Web site, http://walt.allthingsd.com.

Write to Walter S. Mossberg at mossberg@wsj.com

Can you recommend a device that would allow me to surf the Web on a bedroom television connected via Ethernet and to control the device via a wireless keyboard or remote control?

Perhaps the most direct approach would be to buy the MSN TV 2 device from Microsoft that is specifically meant for browsing the Web on a TV from a distance and can be used with Ethernet. It costs $200, plus a monthly fee, comes with a wireless keyboard and remote, and can be ordered at msntv.com.

A second option would be to buy a small computer with a wireless keyboard and hook it up to the bedroom TV instead of to a computer monitor. For instance, I have surfed the Web this way using a tiny $599 Mac Mini computer from Apple, which comes with a wireless remote and accepts almost any wireless keyboard, though it doesn’t come with one. There are numerous Windows computers that could do the same, and many cost less, though most are larger.

Another method would be to use a game console capable of surfing the Web, even if you have no intention of playing games. These are made to work with TV sets, and some can use a wireless keyboard and/or wireless controller to do the job. For instance, the $250 Nintendo Wii game machine has an optional Web-browsing function.

Apple has released a Windows beta version of Safari. Is it any safer to use than Microsoft’s Internet Explorer?

It’s too early to tell, as the Windows version of Safari is still in beta and is very new, to users and hackers alike.

Certainly, operating in Windows will make Safari much more vulnerable to attack than it is on the Macintosh operating system, if only because the writers of malicious software aim their firepower overwhelmingly at Windows. While Internet Explorer is hardly impregnable, it has become safer over the years, and Microsoft certainly has much more experience battling Windows security issues than Apple does. Apple has already issued some security updates for this new version of Safari and will undoubtedly have to keep issuing more to keep ahead of the bad guys.

I am thinking of buying a ThinkPad laptop from Lenovo with AT&T BroadbandConnect. Do I still need to buy some sort of card from AT&T and insert it into the laptop, and must I pay a subscription fee to them?

No, and yes. The laptop likely has the modem for AT&T built in, so you can connect to the Internet via AT&T’s cellular network without buying an external card. However, the service isn’t free. You can’t use it without a subscription, which typically runs $60 a month.

You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

Write to Walter S. Mossberg at mossberg@wsj.com