A desktop computer at home, one at work and a laptop for the road...

If you're like us you're probably using multiple machines every single day, and you'll need access to the same files on each one.

One solution is to carry your important work around on a USB stick - but nothing beats having access to a full backup, whether on an external drive, your laptop or online.

We pick the 15 best tools and services for synchronising and backing up your files.

1. Syncplicity
Easy to install on Mac or PC, Syncplicity backs up folders and files of your choosing to its cloud of servers. Working transparently once configured, you get 2GB of storage on two machines for free. 50GB for unlimited machines is $9.99 a month.

2. Live Sync
The first of three free-to-use entries from Microsoft, Live Sync enables you to access files and folders on a designated machine from any other computer. Your Windows Live ID is the key to all your files, allowing easy synchronisation between machines.

3. Live Mesh
Currently in beta but destined, we presume, to eventually replace Live Sync - Microsoft Live Mesh boasts similar computer-to-computer synchronisation features, but also allows you to back up files to the web using Live Desktop, with 5GB of free storage. There's Mac support coming too.

4. SyncToy
Aimed primarily at photographers, Microsoft SyncToy is free Windows software for creating and updating duplicate folders on separate machines or external drives. Useful for batch renaming, updating back-ups and combing folder contents.

5. Mobile Me
Apples' Mobile Me file synchronisation service came under fire following bugs at launch. It's settled down into a useful tool for storing contacts, files, photos online, syncing with OS X apps, iPhone and - to a lesser extent - Windows. Subscription starts at $99 per year.

6. Dropbox
Available on Mac, Windows and Linux, Dropbox is a transparent tool for backing up files and folders to the web. Files can be shared, accessed online and photos can be displayed in public galleries. A basic 2GB account is free, 50GB storage will cost $9.99 a month.

7. Carbonite
Struggling a little to catch up with a recent influx of young pretenders, Carbonite works in a similar way to Syncplicity and Dropbox, but without their unlimited machine licensing. At $49.95 per year, it's great for simple back-ups on Mac and Windows.

8. MozyHome Free
Available on Mac and Windows, with unlimited backup for $4.95 a month and 2GB for free, Mozy fits the standard commercial pattern - but can handle unusual synchronisation jobs like Exchange, Outlook and SQL databases. Files are stored with 448 bit encryption for maximum security.

9. SyncBack Freeware
Free Windows software for synchronising dedicated files or folders between two machines. With SyncBack you can also back up to an FTP server or over a network - making it ideal for creating a "roll your own" online synchronisation solution. Commercial versions are available too.

10. Second Copy
Second Copy for Windows synchronises files to and from any computer accessible location. Choose to simply copy, compress or synchronise between folders and configure advanced settings to select which fields to backup.

11. Allway Sync
Freeware, Windows-based synchronisation software with support for multiple file systems, can be used to backup in "one way" mode or sync. Best of all? Allway Sync runs from a USB Flash drive, making it the most portable solution. One for the toolkit.

12. ChronoSynch
The best commercial synchronisation tool for the Mac, ChronoSync will set you back $40. It not only synchronises files to external drives and networked machines, it creates bootable back-ups. Detailed log analysis tools enable you to check that you sync has gone swimmingly.

13. Unison File Synchroniser
Hardcore Linux users may prefer rsync - but we're suggesting Unison for its easier interface and cross-platform support. Running on Mac, Windows and multiple UNIX flavours, Unison synchronises between folders. It doesn't matter where your changes are made.

14. DirSync Pro
Fully open source, rather than just freeware, DirSync Pro is a lightweight backup and sync tool for Windows, Linux or Mac. Programmed in Java, you can carry it around on a USB stick and use it to synchronise between different file systems.

15. GBridge
An extension that sits on top of Google Talk, GBridge enables you to create a VPN between designated machines, sharing folders, automatically syncing files and even sharing your desktop. Access your own machines or your Google Talk-using friends. A bit like Live Mesh, but more Google-centric.

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