Holiday time is gift time, and among the gifts commonly given and received are new computers. What, then, should you do with your old PC?

Whether you use computers in your home, small office, or large organization, you have five main choices: You can sell, donate, recycle, reuse, or trash it.

Placing a PC out with the garbage may be common enough, but it’s the worst option. It just fills up landfills and can potentially pollute underground aquifers with lead, mercury, cadmium, and other toxic substances. It’s also a waste.

If the computer is 2 years old or newer, you can try selling it on eBay, placing a classified ad in your local newspaper, or selling it to a used computer store that may advertise in the local yellow pages. Don’t expect to obtain nearly as much as you paid, however, because PC technology advances quickly and prices of new and more powerful computers are relatively low.

A lot of organizations and families reuse older computers by passing them down the hierarchy, giving new PCs to those who can benefit most from the extra speed or capacity. Other options include coming up with new uses for the old PC, such as using it as a file server, print server, Internet gateway, Web server, or home security controller. You can also keep an older PC or two around to salvage parts—such a keyboard, mouse, monitor, or hard drive—as needed.

Donating a computer to an organization that can use it can be a very worthy option. Local organizations that sometimes accept computer donations include schools, churches, senior centers, libraries, shelters for the homeless or battered women, the Salvation Army, Goodwill Industries, and other nonprofits. Such organizations, however, sometimes have minimum requirements for computer donations—for example, the PC must be a Pentium II or later model.

Some nonprofit organizations are set up specifically to receive computer donations and to forward them to appropriate groups or families. One way to find one near you is to go to Google and type in “donate computers .org” (without the quotation marks) followed by your city or town or a nearby city.

Rather than going through an organization, some people enjoy personally doing the work of finding nearby families with children who could use a functioning PC but may not be able to afford a new one themselves.

If you do sell or donate a computer, you should take some precautions to prevent personal information you may have stored on your hard drive from getting into the wrong hands. Simply deleting the relevant files isn’t good enough because this just deletes pointers to the files without deleting the actual data. Similarly, reformatting the drive also makes it possible for someone with a modicum of knowledge to later retrieve your data.

The best way to go is to use a file shredder, which repeatedly overwrites the data to ensure that it can’t be recovered. These utility programs often come bundled in other software such as McAfee Internet Security Suite, or you can use stand-alone freeware programs such as Simple File Shredder (www.scar5.com). Some people go to the extreme of removing a computer’s hard drive and smashing it with a hammer or sledge hammer to destroy all of the data on it. This, of course, destroys the drive itself as well.

If the PC isn’t functioning, one option is to take it to a computer recycling facility, which will retrieve the usable parts and materials. To find one near you, Google “recycle computers .org” followed by the name of your city or town. Some computer recyclers charge a small drop-off fee. Some cities and towns have an annual recycling day when you can drop off old equipment for free. Similarly, some computer and consumer electronics stores accept donations of old computers without charge.

Computer manufacturers such as Hewlett-Packard have trade-in programs (www.hp.com/united-states/tradein). If you plan to buy a new PC from HP, for instance, you can contact the company to provide details about the old PC you’d like to trade in (it can be a brand other than HP) and get an online quote. After buying the new PC from HP, you ship your old one to the company and get cash back. HP then recycles the old machine.

Here’s an additional option to discard a working PC for those who’d prefer to make minimal effort: On a sunny day place the PC outside near the street with a sign taped to it reading, “Free Working Computer.”