A: The built-in backup program in your iMacs, called Time Machine, doesn’t require Apple’s Time Capsule product to work. It will work with almost any brand of directly connected external hard disk.

For instance, I back up my home iMac to a Western Digital drive that’s connected to it via a cable.

As for hard-drive life, it’s my experience that many seem to die sooner or later, especially if they are used heavily. I don’t know if the ones inside the Time Capsule are especially fragile. But, in just the past six months, I’ve had an external hard disk from G-Tech die on me; seen an internal hard disk on my home Dell die for a second time; and discovered that the hard disk on my colleague’s MacBook died.

One way to protect against the failure of a local backup drive is to consider, in addition to using an external disk, backing up your data to an online backup service like Mozy, Carbonite or SugarSync.

My Dell has Microsoft Vista but I can upgrade free to the new Windows 7. However, I was told my antivirus software won’t be compatible and my email will change—the program will no longer be “Windows Mail.” What do you recommend?

A: I regard Windows 7 as much better than Vista, but you are correct that many antivirus programs will require upgrading and Windows Mail will go away during the upgrade. You’ll have to install a new email program, such as the very similar “Windows Live Mail,” which can import your messages. So, the question really is one of trade-offs. If you’re satisfied with Vista, and would rather not perform these program replacements, you should stand pat. If you don’t like Vista, and are anxious to replace it, then the hassles you describe could be worth it.

Will Office 2003 work with the new Windows 7 operating system?

A: Microsoft, which makes both products, says the answer is yes, though I haven’t tested it.

Is it possible that the Verizon Motorola Droid, which doesn’t work in Europe, could be turned into a “world phone” that could work on European cellphone networks via an app somebody might develop?

A: An app wouldn’t be able to do that for the current Verizon Droid. It’s a hardware issue.

Verizon’s Droid, like most Verizon phones, is built to run on a type of network called CDMA that isn’t used in Europe or most other countries outside the U.S., which use a network standard called GSM.

To run on these networks, the Droid, or any other current CDMA phone, would need an entirely different radio, or two radios, one for each type of network.

Verizon offers a handful of so-called “world phones,” which have both kinds of radios inside, but the Droid isn’t one of them. Motorola may well make a new model with two radios, or even a model with one radio that would work overseas, and I wouldn’t be surprised if it did so.

What could be done with an app is to allow the Droid to make so-called VOIP phone calls via the Internet.

In fact, while I haven’t checked, there may already be such an app for Android—the Droid’s operating system—that would do so. But, in many cases, making such Internet phone calls requires the user to be in range of a Wi-Fi network. Some carriers don’t allow such calls to be made over their cellular networks.

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

Does the new Palm Pre smart phone use the traditional Palm operating system and the many programs that have been written for it?

Palm’s Pre, which is due out later this year to compete with the iPhone and the BlackBerry, doesn’t use this older software, which was once the best smart-phone operating system, but has grown stale. It uses an entirely new operating system called the Palm webOS, which will have to attract developers willing to write new programs for it. It is a clean break from Palm’s previous hardware and software.

How does the Clickfree computer backup system you covered last week compare with Apple’s Time Machine or online backup services like Mozy or Carbonite?

Clickfree simplifies the chore of backing up files to an external hard disk. However, as I noted in the review, it doesn’t back up your whole hard disk, it doesn’t work automatically in the background, and it doesn’t create a backup physically distant from your computer.

Time Machine, which is built into the Macintosh operating system, automatically backs up your entire computer in the background and includes a very easy method for recovering files. It works with external hard disks. But it doesn’t work on Windows PCs, and it doesn’t create a remote backup over the Internet.

Mozy and Carbonite are online backup solutions. Their advantages are that they work unattended and create offsite backups. But they aren’t intended to back up an entire computer, they don’t create a local backup, and they carry service fees.

Does my 13-inch MacBook come with the capability to view PowerPoint files?

No. While Macs come out of the box with the ability to view and create files in the Microsoft Word and Adobe PDF formats, they don’t come with a PowerPoint viewer. In order to view (and create) PowerPoint files on a Mac, your best bet is to buy the Macintosh version of Microsoft Office, which includes PowerPoint itself. There are other methods as well. For instance, Apple’s own lower-priced iWork suite can also open PowerPoint files and create files in the PowerPoint format. And some Web-based office programs, like Google Docs, allow you to view PowerPoint files on Macs.

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 can’t figure out how to remove a song from my iPhone. How do I do it?

Unlike an iPod, the iPhone has no purely manual-mode option, which would allow you to drag songs on and off of it. However, there are alternative methods.

The simplest approach is to connect your iPhone to your Windows PC or Mac, and allow it to synchronize as usual. Then, select your iPhone in the list at the left edge of the iTunes window in order to bring up the iPhone-settings functions in the large window at the right in iTunes. Click on the Summary tab, and check the option called “Only sync checked items.” This will limit the songs and videos the computer places on the iPhone to those for which you have checked the little box that appears next to their names in iTunes. Next, go into your music library, or into any playlists you have selected for syncing with the phone, and uncheck any songs you no longer want on your iPhone. The next time you perform a sync, these songs will be removed from the phone.

Another method is to place all the songs you want on the iPhone into a single specially designed playlist, or several such playlists. Then, go to the Music tab in the iTunes settings screen and click on “Selected Playlists.” Next, check off only your special iPhone-bound playlists. Once this is done, you can control which songs are, or aren’t, synchronized to the iPhone by adding or removing songs from these playlists. If you remove a song from one of these playlists, it will be deleted from the iPhone the next time you perform a sync.

Neither of these methods will delete the songs from your computer or your iTunes library, or prevent them from playing on your computer.

I have tried to download some pictures recently and use them as wallpaper. I am storing them in my My Pictures folder. But, when I choose to make them my wallpaper, they appear multiple times on my desktop. How can I have a picture cover the whole background on my monitor?

Assuming you are using Windows XP, go to the Display control panel and select Desktop, then find the image in the Background list and select it. Then, under Position on the right, select Center or Stretch. Note, however, that if you have downloaded a small image from the Web, and your monitor has a relatively high resolution, the Center option won’t allow the image to fill much of the screen. The Stretch option, while filling the screen, may result in a grainy and/or distorted image.

I was wondering if you could recommend a good service for automated online backup of a PC running Vista. All the services I have found require the user to manually transfer files to the online site. In my ideal world, I could set up my machine to transfer the files during the evening.

There are two automated online backup services I’ve tested and reviewed, Mozy (mozy.com) and Carbonite (carbonite.com).

Both work on Vista, neither requires manual file transfers, and both are good, though I preferred Mozy when I last tried them in December 2006. However, Carbonite has released a new version I haven’t tried yet, and Mozy has also been updated since then. I don’t think you’d go wrong with either. You can read my review at ptech.allthingsd.com/20061214.

Mozy offers two gigabytes of backups free, and charges $4.95 a month for unlimited backup, though you can save by paying one year or two years in advance. Carbonite offers a 15-day free trial, after which you pay $50 a year for unlimited backup, though you can save if you pay upfront for two years.

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

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