People resort to all sorts of time-consuming methods for doing this. Some email the items to themselves. Others copy them to USB thumb drives and manually transfer them to each machine. Still others use Internet-based, or “cloud,” storage, uploading all their photos to a service like Flickr or Facebook, or using Web-based productivity programs like Google Docs (GOOG). And some use Web-based backup, storage or synchronization services.

Each of these methods, even the cloud-based ones, has limitations and frustrations. Some are complicated, or work only with certain kinds of files. Others work only when you have a Web connection, or don’t replicate your preferred folder structure. Still, others work OK with standard files and folders, but have trouble with specially arranged content, such as music that is organized in a jukebox program.

I’ve been testing a cloud-based service that attempts to solve these problems. It is called ZumoDrive, and it comes from a small company called Zecter Inc. A new version is due out this week that aims to add some capability and make the task simpler.

ZumoDrive mimics a standard physical hard disk, which can contain numerous folders and files. It works on Windows, Macintosh or Linux computers, and also comes in a more limited version for the Apple iPhone. It presents itself as a standard hard-disk icon on all your computers. But it’s actually a single, identical virtual hard disk that lives on the company’s servers, not on the computers themselves. The files it contains are rapidly streamed down to your machines when you need them.

I tested the service on a desktop Windows PC, a netbook, two Mac laptops and an iPhone. I generally liked ZumoDrive and found it easy to use, and pretty fast. But I ran into a few glitches, and it can be pricey. The new version will offer 2 gigabytes of storage free, but will cost a monthly or annual fee for more storage, ranging from $30 a year for 10 gigabytes to $800 a year for 500 gigabytes.

Also, like all cloud-based storage, ZumoDrive isn’t fully accessible when you’re offline. It caches, or automatically downloads, some recently used files, making them available offline. But you may want to open a document or play a song that is available only when you are online.

There have been online storage services for years, including some that could appear as desktop icons. In particular, ZumoDrive competes with somewhat similar services such as SugarSync and DropBox. But it’s different.

Unlike DropBox, it doesn’t require you to remember to place files in a single, special folder. You can link your existing folders to the ZumoDrive. And, unlike SugarSync, it doesn’t copy all your shared files to the hard disks of all your computers. It keeps the files in the cloud.

Compared with SugarSync, which I also like, ZumoDrive uses much less of your hard disk space, and does a better job with iTunes libraries. But SugarSync doesn’t require you to be online to use the files it synchronizes, though it also keeps a backup copy that you can access from the Web.

You don’t need to learn any special techniques to use ZumoDrive. Your computer sees the ZumoDrive as if it were a physical hard disk, so you can add and delete files to it in the normal ways. A program like Microsoft Word (MSFT) also sees it as a normal disk, and can open files from, or save them to, a ZumoDrive without a second thought.

And, because a ZumoDrive can be large without taking up much space on your local drive, it is especially nice for netbooks, which may offer relatively little storage. It also allows you to share folders with others, and encrypts the data you store on it, for security.

To use ZumoDrive, you first upload all your key stuff from your main computer. Then, once you install the small ZumoDrive program on your other devices, all those file names show up on your screen and can be fetched from the cloud when you like. You can add files and folders from the other computers as well. And you can also access your files via a Web site or an iPhone.

You can link folders on your computers to identical folders on your ZumoDrive, and they will stay in sync, so you can keep using the folder structure you’re used to, and it will be up-to-date on the ZumoDrive.

ZumoDrive understands how to handle and centralize your iTunes music library. In my tests, I uploaded an iTunes library of about 900 songs from a Mac at my home, and was able to play the songs on a Windows XP netbook that had no music stored locally.

I ran into some glitches and limitations, all of which the company says it is fixing. For instance, at first my netbook didn’t fetch all the iTunes songs.

But, all in all, ZumoDrive is a harbinger of the new world of cloud computing, and it is worth a look.

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.

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.

There are networked hard drives from several manufacturers that can back up both laptops wirelessly and allow sharing. One I reviewed recently is the My Book World Edition from Western Digital. Another approach would be to use a Web-based synchronization service. My favorite of these is called SugarSync, from a company called Sharpcast.

SugarSync can automatically, and almost instantly, synchronize files in folders you select among multiple computers, while also backing them up to a password-protected Web account. SugarSync starts at $5 a month or $50 a year for 30 gigabytes of files, and goes up in price based on the amount you use. The company offers a free two-gigabyte account and a free trial of larger accounts for 30 days. More information is at sharpcast.com.

I have been a Windows user for may years but have wanted to change to Mac. Yet every article I read says that Quicken, which I depend upon heavily, will not run—at least reliably—on a Mac, even with the Windows-compatible software. Is this true?

The native Quicken version for the Mac is a less capable program than the Windows version, and doesn’t use the same file format, which makes importing Windows Quicken files a tedious and imperfect process for many users. Intuit, the maker of Quicken, is promising a new, much better native Mac version early next year that it claims will solve these problems, but I haven’t tested it, so I can’t verify that pledge.

However, in tests I have run periodically, Quicken for Windows ran just fine on a Mac equipped to run Windows and Windows programs. This was true when I used either Parallels or Fusion, which allow you to run Windows programs on a Mac simultaneously with Mac programs; or when I used Boot Camp, which converts the Mac into a full-fledged Windows machine, with Apple’s operating system turned off.

I plan to get a new computer after Windows 7 is released in October, to replace my old Compaq running Windows XP. Will I have difficulty moving my files to the new one?

You shouldn’t have much difficulty with your personal data files. Microsoft is building in an Easy Transfer program to move personal files to a new Windows 7 PC. But the Microsoft program won’t move over your programs. You will have to reinstall all your programs, which means finding your installation disks or installer files and re-installing all the updates from that have occurred over the years. A company called LapLink is promising to sell software it says will automate the entire process, including moving programs, to spare you this re-installation burden. But it isn’t out yet, and I haven’t tested it with Windows 7.

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

Has anyone come up with a method that allows people to take pictures with a regular digital camera and then download them wirelessly to a computer, and/or perhaps to the Internet?

There have been a few digital cameras with built-in Wi-Fi wireless capability, but the best and simplest method I know is a $100 product called Eye-Fi. This tiny gadget looks and works like a regular, garden-variety SD memory card, but it packs a Wi-Fi transmitter inside. It fits into a standard SD memory-card slot and is compatible with a wide range of camera models from Canon (CAJ), Kodak (EK), Nikon (NINOF.PK) and others.

Coupled with clever software, and a clever Web site, the Eye-Fi card automatically zips your pictures wirelessly to your PC or Mac, and/or to your choice of over 20 online photo-sharing services.

For more information, see www.eye.fi. For a list of compatible cameras, see support.eye.fi/compatibility/. For a full review of the product, see: solution.allthingsd.com/20071121/.

You mentioned last week that SugarSync might be a good solution for backups, so if one computer dies your files still exist on another system. But what if the doomed computer doesn’t actually die but its files are corrupted by malicious software? Do those newly corrupted files overwrite the good copies on your SugarSync network?

They could do so, depending on which folders you had chosen to replicate on your other computers. Automatic-synchronization services like SugarSync have a tough time telling whether changes to a file are deliberate, accidental or the result of some sort of corruption. Though the last is rare, it could look to SugarSync like you had changed the file on purpose.

One way to guard against that is for a service to offer “versioning” — the practice of maintaining multiple past copies of a file. That way, if a change isn’t intentional, you can go back to the prior, pristine version. Sharpcast, the company that makes SugarSync, says it is planning to add versioning to the service, but offers no specific date. In the meantime, one way to back up a file without fear of its being overwritten by a corrupted version is to upload it to SugarSync’s special “Web Archive” folder, whose contents are never automatically updated.

Have you ever reviewed and suggested a media player for connecting to a home theater to play all songs, videos and photos that exist on your home computers?

Yes, I have reviewed several over the years. The one I find simplest and best designed is Apple TV, which, despite its name, can work fine in a household with no other Apple (AAPL) hardware. It costs $229 and is a small, thin, unobtrusive box that fetches music, photos and videos from your home network using either a wired or a wireless connection. It can connect to your TV set or home theater via a variety of analog and digital ports, including component-video, HDMI, and optical and analog audio. It supports high-definition video and works with any computer, Windows or Mac, that has Apple’s free iTunes software installed and running.

Apple TV handles many standard photo, music and video formats, but it is limited to music and video files that iTunes can handle. That excludes copy-protected files in Microsoft’s formats, and certain open Microsoft formats, but includes common files like MP3s. Apple TV also allows you to access YouTube and to purchase music and TV shows from Apple, and rent movies from Apple, without the use of a computer.

• 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.

Now, there’s a new service called SugarSync that keeps your files replicated and synchronized across all your computers, whether they are Windows PCs or Macs. It even offers limited file synchronization on certain smart phones. The service is from a Silicon Valley company called Sharpcast and is available at sugarsync.com.

Not only does SugarSync place the latest version of every file you designate for syncing on all your chosen computers, but it also creates an archive of these files on a special, password-protected Web page. That way, you can access the latest version of any file even when you are at a public or borrowed computer that lacks the SugarSync software.

I have been testing SugarSync on five different computers — three Windows PCs and two Macs — as well as on a Treo smart phone. I tried syncing everything from Excel spreadsheets to Word documents, from photos to songs to PDF documents.

My verdict: While SugarSync isn’t free and has a few rough edges, it is by far the best solution I have tested to replicating and synchronizing your files across multiple computers. It really works.

Every time you change a file — say, by editing a Microsoft Word document or rotating a photo — the changes are replicated within seconds on every computer to which it has been synced and in the Web archive as well, as long as the computers are connected to the Internet.

For example, I set up SugarSync to synchronize a folder containing some Word documents. Then, I opened one of the documents on a Dell and added a sentence to it. A minute later, I opened the same file on a Mac, which was also connected to my SugarSync network. The file already had been updated on the Mac to include the change I had made on the Dell.

While SugarSync is primarily about file replication across computers, it also helps solve another nagging problem: backups. Because the files you care about most are now replicated on multiple machines in multiple places, and are stored as well in a Web archive, they are also backed up. So if one of your machines dies, you don’t lose your files. And, if you find yourself in need of a file that doesn’t exist on the computer in front of you, it can be downloaded.

SugarSync works by uploading your synchronized files to its servers, in encrypted form, and then sending them down to your computers when they change. There is a 45-day free trial that gives you 10 gigabytes of file storage. After that, you can keep the 10 gigabytes for $25 a year. There are five other storage plans, ranging from $50 a year for 30 gigabytes to $250 a year for 250 gigabytes.

The software that makes it all possible, called SugarSync Manager, is free and comes in Windows and Mac versions, as well as versions for Windows Mobile phones and certain BlackBerry models. An iPhone version is in the works, but for now, you can scan your online archive using a special SugarSync page available through the iPhone’s Web browser.

You install the manager software on any computer you wish to be part of the synchronized network. You can select different folders on different computers for syncing. All get uploaded to the Web archive, where they can be accessed at will.

You can choose which folders you wish to replicate fully on each machine. For instance, you might want your main documents folder to be replicated on every hard disk, available even when you’re offline. But, with a folder of lesser importance, you might be content to just fetch a file when you need it from the Web archive.

SugarSync creates two special folders. One, called Magic Briefcase, is always replicated on every machine’s hard disk, so you can quickly add a file to it even if you didn’t select the file’s original folder for synchronization. The other, called Web Archive, retains files in their original versions, never updating or changing them.

So, what are the rough edges I spoke about?

Well, the Mac version of SugarSync manager is still in beta, crashes occasionally and has various bugs. A final Mac version is promised later this spring. The cellphone versions can only view photos and whatever documents the phones allow, but changes you make on the phones in documents other than photos aren’t synced back to the computers or to the Web site.

In addition, SugarSync can’t synchronize Microsoft Outlook files and it can’t, say, replicate a new calendar entry or contact change across your computers. The company has shown off this capacity in public demonstrations and says it is working on adding it.

Still, SugarSync solves a real problem and does so well.

• 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.