Relying on desktop or portable storage devices to safeguard files isn't always ideal. They can break down or be lost.
Internet companies such as Yahoo! and AOL (and soon Google), along with smaller competitors, have addressed these problems by allowing users to store nearly any kind of file on their secure servers. The stored files can then be retrieved from any internet-connected computer, and you can also share your files with others. Some firms charge a fee for these services; others offer them free.
Perhaps the best thing about online storage is that it's easy to fathom - many of us are used to uploading files to the internet.
A broadband connection is essential. Storing files - particularly digital photos and MP3s - takes an eternity even with a high-speed connection. Without one, it doesn't bear thinking about.
Turning your digital camera into a mobile photo album. Because computer hard drives are never big enough, it makes sense to use the biggest memory card available in your camera. That way, you've got dedicated storage and you only have to load pictures on to your PC for editing. The screen on the back of the camera becomes a way of viewing not only recent shots, but your old favourites too.
The good thing is that memory cards for digital cameras are getting bigger and bigger. The manufacturer SanDisk has just introduced its new Extreme IV line of compact flash memory cards, which offer up to 8GB of storage and deliver minimum read and write speeds of 40MB per second, making them the fastest flash memory cards in the world.
There are many types of memory card, and you need to make sure you have the right one for your camera. "Compact flash" cards are gradually being superseded by SD/MMC, a smaller type of flash memory, which originally had a storage limit of 2GB but now has 4GB. The XD picture card is yet another type of flash memory, currently offering storage capacities of between 16MB and 1GB, depending on your budget. If you use a Sony camera, the company's proprietary memory sticks are another storage option offering increasingly high capacity (Sony unveiled an 8GB card at the 2006 Consumer Electronics Show in Las Vegas).
This won't be much help if you need to back up your music collection.
Sony MSX-1G Memory Stick Pro costs £90 ( www.pcworld.co.uk). Fuji's 512MB XD picture card costs as little as £17 ( www.amazon.co.uk) and the SanDisk Ultra 2 (above) offers 2GB for £54.99 ( www.fotosense.co.uk).
USB FLASH DRIVES
USB flash drives (also known as pen drives, or USB memory sticks) are great for moving relatively small amounts of data between computers, or between work or university and home. They range from 32MB to several gigabytes.
Slot the stick into your computer's USB port and it appears as a removable drive. You can then drag and drop files to and from the device, as you would between folders and directories.
The drives are a lot more convenient than CD-R or CD-RW discs for quick back-ups as you can write to them instantly (with CDs you need to queue files to burn). Flash drives are robust and impervious to the scratches and dust that cause problems with CDs.
USB is the standard port for plugging in printers, digital cameras, or any other computer add-ons.
Flash drives wear out. But the more expensive drives will last for several million cycles of writing and erasing before slowing down and possibly packing in. Some computers' anti-virus software may prevent use of flash drives.
Depending on how much storage you need, choose one of the following: ByteStor 1GB portable flash drive, £18 ( www.amazon.co.uk); CN Memory 2GB portable flash drive, £28.97 ( www.pcworld.co.uk); PNY, 4GB, £90 ( www.pcworld.co.uk).
USE YOUR MP3 PLAYER
Most people have plenty of unused space on their iPods. According to a study from Solutions Research Group, the average MP3 player (all brands) has 375 songs on it - yet the 60GB iPod can hold up to 15,000 songs. So it makes sense to use your iPod as a backup device. Music fan should plough their cash into a top-of-the-range fifth-generation iPod (holding up to 60GB of data) rather than a cheaper MP3 player and a backup device.
Most MP3 players are in fact fancy flash drives - or hard drives, if you have an older model. This is why they double very nicely as external drives for backing up files.
The more you store, the less music you can carry with you. And an MP3 player is always at risk of being stolen or lost.
The Apple iPod (60GB) has a screen to view pictures. It costs £299 (www.apple.com). The 4GB Creative Zen Micro (right) Photo is similar and costs £99 (Pixmania.co.uk).
EXTERNAL HARD DRIVES
Regular backups of your critical data. External hard drives are easy to install and provide a massive amount of extra storage, ranging in capacity from about 80GB to 400GB. At the top end, that's almost certainly larger than the hard drive inside your computer, so you can backup everything you have just in case the worst happens to your PC. You can schedule regular back-ups (a very wise move) to safeguard all your documents, photos and MP3 files without your having to remember to do it.
External hard drives are also very useful if your existing hard drive is chock-full of MP3s and video clips and you need extra storage. You should find that your computer works faster if you delete some of the files after they've been backed up.
Portable hard drives are another option. They have smaller capacities and cost more than their desktop counterparts, but the pay-off is that they're lightweight and robust, making them an ideal solution if you need to transport large amounts of data around, say, in your laptop bag.
Depending on the model, desktop and portable hard drives support either USB 2.0 or FireWire, or both. USB and FireWire are high-speed interfaces connecting your computer to outboard hardware. The jury is out as to which is the fastest - much of it depends on the computer they are connected to. So, if you can, choose products that support both and try them out.
External hard drives aren't as fast as the one that's inside your PC or Mac.
Freecom's 320GB external hard drive is a good all-rounder; it costs £110 ( www.pcworld.co.uk). As a portable option, the Pikaone SFLS-U2-40 (above) is a 40GB slimline portable hard drive costing £80 ( www.pcworld.co.uk).
BURN ON TO A DVD
Storing files on DVDs is a good low-cost storage solution if you're not dealing with masses of data, especially if, like many home PCs, your computer has a built-in DVD burner. If not, you'll need to buy one (see below).
This is an excellent way to archive libraries of digital photos, video clips and music files, along with work or business data that you don't need regular access to - your end-of-year accounts, for example.
There are different types of DVD. Standard single-layer discs provide 4.7GB of recording space, while dual-layer versions (labelled on the packaging as DVD+R DL and DVD-R DL) - which look identical but have two separate recording layers on a single-sided disc - provide 8.5GB. Not all DVD drives can write on to dual-layer discs, but once recorded, dual-layer discs can be read by most DVD players on the market.
Discs labelled "DVD R" (which cost as little as 17p per disc) are for single use, whereas "DVD RW" (35p for single-layer; from £1.50 for dual-layer) versions can be wiped and used again and again - perfect for backing up accounts each month or taking your pictures to the high street to be printed. The numbers - 16X, 8X etc - denote the speed at which the drives read and write information; the higher the number, the faster it will work.
Some DVD burners are faster than others, but storing 8.5GB on to disc can take half an hour.
The NEC ND4570 shows just how cheap double-layer DVD writers can be; it costs just £26 ( www.novatech.co.uk). For a more feature-packed option, try Samsung's SE-S164L, at £79.99 ( www.maplin.co.uk). For portability, the Philips Lightscribe SPD3200CC costs about £95 ( www.pcworld.co.uk).
Computer storage may be about to change for good. "Flash [the kind of memory used in MP3 players] is definitely a thing of the future," says Paul Motion of the memory manufacturer Crucial Technology. "It may replace hard disks. Flash is smaller, more robust, produces less heat and is more energy efficient."
The downside of flash is that it doesn't currently have the high storage capacity of hard disks. However, Samsung is developing a laptop that doesn't have a hard drive at all, but uses 32GB of flash memory instead. Flash is also very light compared with hard drives, which means that laptops will become even more slimline and lightweight in future.
Lexar's PowerToGo system has already taken advantage of the growing storage capacity of flash memory. It essentially turns any available PC into your PC, complete with not just your own documents, but software, e-mail, browser shortcuts and more. It's the perfect solution for students who use computers in different college classrooms and for business executives who use computers in hotels and trade show centres.
Other experts, however, believe that magnetoresistive random access memory (MRAM) - a new kind of memory chip altogether - will one day be the successor of the hard drive. Freescale Semiconductor, its developer, claims that it is faster than flash memory and doesn't deteriorate after repeated use.