By Nick Peers

If you want to back up a CD, DVD or Blu-ray disc, then the ISO file offers the opportunity to take advantage of all that spare capacity on your backup drive, using that as a storage medium for your backed up discs. ISO files are exact images of discs, which also comes in handy when you, or someone else, wants to distribute a CD without incurring the costs of burning a disc and posting it.

Windows 7 has some limited support for ISO files built-in: you can create an ISO file from a disc, or burn a disc from an ISO file using tools built into the OS, but what if you're using an earlier version of Windows, or you've been handed a disc image in a format other than ISO? The quick, simple and completely free answer is