Washington  - Most of us have a box or book of old photographs somewhere - precious memories of times and people we hold dear.

Thanks to the paper on which those photos are printed - and the ease with which paper can be handed down - those memories are intact.

But what about future generations? If we copy our digital photographs, video, or sound clips onto CDs or DVDs, will our heirs even have the equipment necessary to read them?

It's a question that deserves careful consideration, especially since many of us today are spending countless hours amassing irreplaceable memories and, for the first time, entrusting those memories to various forms of media that are not only fragile but can also quickly become obsolete.

That's why if you want to pass down the memories that you're capturing with your digital equipment, it's vital that you develop a strategy for preserving them - and to know the pros and cons of the various storage media available today.

--- CDs and DVDs

CDs and DVDs are the first types of storage people think about when they want to copy some files and stash them for future generations. Unfortunately, there are a couple of serious problems with this approach. First, the longevity of writable CD and DVD disks varies greatly. Some early writable CD disks that were supposed to last for 40 years or more have been known to become completely unreadable after only a couple of years in storage. And today's bargain-priced writable CDs and DVDs are generally not sold on the basis of how long they'll last.

Responding to the demand for more dependable, "archival" quality disks, however, some firms - including Verbatim, Memorex, and Fuji Film - have created special archival-quality writable media. These disks have a data surface that optimises both the recording performance and the longevity of the disks themselves. They're more expensive, as you might imagine, but if you're using your disks to preserve memories, a little added cost should not be your primary consideration.

Archival or not, what might be of more concern is the rapid pace of progress in technology - and the possibility that the CDs and DVDs you create for posterity today won't even be readable by the computer equipment in use a generation from now. A look at recent history tells the story. Twenty years ago, the 5 1/4-inch floppy drive was ubiquitous. Today, floppy drive readers of that size are impossible to find at most electronics retailers. If you had some precious files stored on a 5 1/4 inch floppy drive, you'd have to go to great lengths today to find a computer that could read the disk.

--- Hard drives and flash drives

If the digital memories you want to hand down consume lots and lots of storage space, hard drives might be your best choice. The way to go here would be to purchase an external hard drive - available now in sizes up to 1.5 terabytes - that can be connected to the computer with a USB cable. Update the drive with your latest files regularly, but otherwise keep the drive in storage to preserve its life expectancy.

The concern with hard drives is that they're relatively fragile. A hard drive "crash" - which refers to the drive's read/write heads bumping into the quickly rotating magnetic platters within the drive - can render all of the data on a drive unreadable in a matter of seconds. At that point, only an expensive repair can salvage the data - if it's salvageable at all.

Solid state drives (SSDs), which are quickly gaining ground on traditional hard drives, are not nearly as fragile. Rather than spinning magnetic platters, SSDs store your data on flash memory chips - the same kind used to store your digital images in your camera. SSDs can be used as drop-in replacements for hard drives.

Unfortunately, they're still quite expensive: While a 1 terabyte traditional hard drive costs 100 dollars today, a 64 gigabyte (GB) SSD retails for about 150 dollars. That makes SSDs almost 10 times the cost of traditional hard drives on a price/capacity basis. SSDs currently top out at around 128 GB, as well. Still, because of the SSD's durability, this is a technology to keep your eye on for archiving precious memories. Prices are bound to come down quickly over the next year.

--- Online storage

Storing at least a copy of your digital memories online makes sense for a couple of reasons. First, you no longer have the concern over whether the media on which you store your files will go bad. Second, any concerns over obsolescence are largely removed. Third, you have a copy of your files off site. And fourth, you'll theoretically be able to access your files from any computer that has an Internet connection.

The problems with online storage are cost, the speed of upload, and concerns about whether the online storage company will be around for the long haul. While many online storage companies provide a limited amount of space for free, digital photos, videos, and audio require huge amounts of storage. So you'll quickly outgrow the amount of storage given out for free, and you'll end up having to pay for extra space. Still, some companies offer unlimited space for a modest monthly fee. Check out Mozy. com, Box. net, and FlipDrive. Also keep an eye on Google, which has long been rumoured to have an online storage product in the works.

In terms of upload speed, you can expect to spend many hours if not days uploading a large library of media files to an online storage vendor. And if the vendor decides to close its doors - as did XDrive recently - then you or someone will be in search of a new home for your digital memories.

--- Solution for the ages

While each type of media you might turn to in order to preserve your digital memories has advantages and disadvantages, there's no fool-proof way to ensure that the digital memories you create today will be around 50 years from now. So if your memories are indeed priceless, you should adopt a strategy that involves both storing your files today and creating instructions for migrating your files to the storage media of the future.

In terms of storing your files today, to be safe, make two copies of every file, and store each copy on a different type of media. You might, for instance, keep one copy on an SSD and another at an online service that's not likely to fail anytime soon.

In addition, type up instructions to be passed along to those who ultimately will take possession of the data. The instructions should include such information as the type of files that are stored, the programs that were used to create them, and a directive to migrate the files to newer storage media as technology changes.

Ultimately, though, even the best-laid plans can go awry, so be sure to enlist the help of "old tech" - for example, paper - when appropriate. Print out your most cherished digital photographs, for example, and keep them along with a digital copy of the originals. After all is said and done, a box of old photographs just might outlast all the high tech we've been able to come up with over the past twenty-five years. (dpa)