Online storage services make a great secondary backup solution because your data is safe in case of burglary or damage from a fire or flood. The services generally provide software for file encryption and for scheduling automated, incremental backups, and they typically store your data at multiple remote locations for increased security. Some sites even let you share files remotely.

The downside of these services is you have to put your trust in a third party to keep your data safe, and that might make you uncomfortable. They're also the slowest of the backup methods we tested, taking anywhere from 10 minutes to 12 hours to upload 1GB of data and 10 minutes to 3 hours to download. In addition to the type of files and the speed of your PC, the variables that account for the huge disparity include what else is happening on your PC during the backup, the speed of your Internet connection, and network traffic both on your end and at the online service. The slowest by far was Carbonite, for both uploading and downloading.

If you have a limited amount of data, you can use one of the free services, and the upload time would be more reasonable. But if you have a lot of data and are frequently adding to it, the glacial speed and the monthly fees can make this a poor long-term choice. If you have a large amount of digital image files, you might want to consider a photo-sharing service, which lets those you invite view and print photos, but uploading will still be slow.

The data-backup service we liked best was Mozy. It offers the most features and control, scheduling backups is easy, and customer service was quick and helpful. The service is free for up to 2GB of data, and $4.95 per month gets you unlimited storage. Another service, Xdrive, lets you store up to 5GB for free; $9.95 per month gets you 50GB.