If you've been using computers for a while, the chances are you've experience the dreadful sinking feeling when you realise a precious file might be lost for ever. We've long used our computers to store personal documents containing vital information - a financial spreadsheet containing incomings, outgoings and the tax we need to pay, for example - but with digital cameras and video, our PCs are now the custodians of our family history and digital heirlooms.

Sadly, they're not infallible. And even if your computers never let you down, anyone who uses them can make a mistake. It's easy to delete the wrong file, and almost as easy to spill food or drink, or drop a laptop computer.

Luckily, it's easier still to make sure that your vital files are safe. Backup programs have been around for almost as long as computers - they store a second copy of your files, giving you a way to get them back if something happens to the original. But with fast home broadband connections such as BT ADSL broadband, it's now practical to store your essential files somewhere else altogether. Even if the unimaginable happens to your home or small office, your vital pictures and documents will be safe in an 'online backup'.

Anyone with an internet connection can use an online backup service, but with BT as your broadband supplier you get access to one free. With BT's Digital Vault, you'll get 5GB of space on BT's secure servers - you can fill it with all the files and photos that you couldn't live without.

That's a lot of space - enough for more than 1,500 photos from a typical digital camera - but for a small monthly fee you can get BT Digital Vault Plus, which gives you ten times as much. Whichever you use, how do you get the most out of it?

Using the web

You can transfer files to and from your Digital Vault using our simple web front-end. Just visit the Digital Vault homepage , and sign up to create your vault. If you're a BT Broadband customer, you'll need to provide your btinternet.com email address - without it you'll only get our basic 1GB service. Once you've signed up, you can send files to your vault from any computer with a broadband connection - just visit the Digital Vault homepage, sign in and click the Upload files tab .

On the next screen, you'll be able to drag and drop files directly into a list that you can backup at the click of a button. You can also browse your computer for one or more files to upload. Once you've made your selection, simply click on the Upload button - a progress meter will let you keep an eye on how things are going, and when you can expect your files to finish copying. After you've uploaded your files, you'll see an overview of your Vault - you can see this at any time by clicking on the My Vault tab .

Although the Digital Vault is designed to keep your files safe and private, you might want to let other people see some of them - perhaps if you've just got back from holiday and you want to share snaps or videos with friends and family. Click on the View Play Share tab to select the files you want to share, and invite selected people to view them.

Automatic for the people

Of course, no matter how easy it is to store files online, you'll need to remember to do it manually. Unless, that is, you subscribe to Digital Vault Plus, which comes with Auto Backup software. You can download and install this from the Digital Vault homepage. Once you've got it installed, you'll need to provide your Digital Vault login details and provide a name for your computer - you can use the software with up to four PCs.

On the next screen you can choose the files and folders that you want Auto Backup to keep safe - simply click the checkbox to mark files for backup, or click again to unmark them. Finally, tell the software how often to check your files for changes. Anything you've added or changed since the last backup will automatically get copied to your vault, so you can relax and be sure that the latest versions of your files are safe.

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