Rolling back a malfunctioning PC to a time when it worked is not new, but Windows’ method, System Restore, is both unreliable and messy, leading to a cluttered and increasingly unreliable computer.

For a backup that can be relied on to save your PC in times of trouble, consider making a complete copy of the disk that Windows is installed on.

This kind of backup is known as a disk image. It can be used to supplant a recovery disc supplied by the manufacturer or provide an additional layer of protection for your files. Better still, it doesn’t cost a penny. We will explain all you need to know.

Choose a method
In the past taking an image of a hard disk meant spending money or using unfriendly software. However, these days it seems there is a free tool for every task and a user-friendly program called Macrium Reflect Free does a good job of simplifying the process.

The key requirement when backing up is choosing an appropriate backup device. It would be madness to store any backup on the same hard disk as the original, so select a suitable alternative.

Macrium Reflect Free supports three backup locations: a network drive, recordable CD/DVD or a second ‘local’ hard disk (one either inside the PC or an external drive connected by USB).

For most people, the easiest option is the last. A local hard disk is quick and easy to restore from and USB models with plenty of storage are very affordable nowadays.

If you are backing up to another drive on a network it might be tricky connecting a poorly PC to a network to perform a restore from a backup. But if you are intent on this method, be sure you know how to do the job ­ do some testing (more on that later).

The final option offered by Macrium is to back up to multiple blank CDs or DVDs. Although the backup is compressed to save space, CDs are not practical, so opt for DVDs instead ­ you may still need several.

Back-up scenarios
The best time to take a drive image is when Windows is running smoothly. Unlike Windows System Restore, which only restores certain files (and is prone to failure when most needed), a disk image preserves an exact copy of the selected hard disk or partition, which means all subsequent changes to it are lost when restoring.

That is great for undoing recent problems, but it also puts your data at risk if it’s stored on the same disk or partition as your Windows files. Take a separate backup with a file-based backup program (Windows 7 and Vista users should type backup into the Start menu’s search box to access a program built into Windows for this task; XP Home users will have to install it first).

If you plan to re-install Windows from scratch, taking a disk image is good for another reason: data protection. Taking an image backup of the old setup as well as a backup of important files ensures that no files or settings are lost.

Macrium makes it possible to retrieve individual files and folders from a backup, so if the main backup is missing a vital file you are covered.

A disk image backup can also be used to replace an original Windows disc or manufacturer-supplied recovery disc. Capture a disk image of your ‘perfect’ Windows setup and later you will be able to restore from this snapshot, rather than having to perform a full re-installation and re-install all your personal software.

However, remember that restoring from a disk image backup will wipe all the existing files on the disk, so do not forget to take a second image before proceeding to ensure that important files are not lost.