All of which sent a cold shiver down the spine. We have image files stored on 22 CDs and one DVD and this led us to wonder just how long they will be accessible. How long will a homemade CD or DVD last? Not long, according to Herr Kurt Gerecke, IBM expert on data storage. Mr Gerecke told the magazine PC World that two years is about the average life expectancy of a burned disc, and if you keep it in a dark, cool place it might last for five.

Not very reassuring. Gerecke says the burned disc has a short lifespan compared with a commercially pressed disc, which fits with our observation. We have compact discs bought on CD Day One in 1983 that are still perfect. On the other hand, we have had DVDs give up the ghost in less than a year. Discs seem to be another of those consumables that obey the inexorable law of capitalism: You get what you pay for. The el-cheapo discs look attractive but they won't last. The pricier brand-name discs do better but only by five years.

The next big thing in optical writeable discs is Blu-ray, which is not yet available, but even that must be seen as an interim medium between non-volatile memory on revolving discs and memory on solid-state devices similar to camera memory cards or memory sticks. Samsung has announced a notebook with 32GB of flash memory and no rotating hard drive. That's the future. So perhaps all we need is five years of optical storage to tide us over. If you're worried, it might be worth looking into the Delkin eFilm Gold CD and DVD blanks. These promise a life of 100 years for the DVDs and 300 for the CDs. Their longevity is attributed to the use of gold in the reflective layer of the disc, according to the Australian distributors, Baltronics. Gold is supposed to be impervious to temperature and humidity and therefore resistant to oxidation.

Given the claims made for the Delkin discs they're not that expensive - $1.72 for a CD and $3.50 for a DVD. They are cheaper in bulk and can be ordered from http://www.photo-accessories.com.au Prints on paper are still the medium most likely to survive in the shoe box. But before investing in a photo ink-jet printer it pays to check the Wilhelm Research webpage (http://www.wilhelm-research.com) for the most recent longevity test results. The superb Epson 2400 printer - or any of the Epson range that uses pigment rather than dye inks - rates highly for life expectancy. Keep your Epson prints in an album or a box and, depending on the paper used, the pictures will still be there in 200 years' time.

Preliminary tests on the forthcoming Canon pigment ink printer show that colour prints will be in good order in 100 years' time and monochrome prints even longer. Pigment inks do not produce prints with the same resolution, colour range and snap as dye inks but the dye-based medium fades faster.

The moral of the story is that digital images might not be as ephemeral as once we feared.